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eagle stone - Agtite, said also to include limonite nodules.

ear lobe dermatitis - Local irritation believed caused by allergic contact with nickel in certain costume jewelry and gold-alloy earrings. Test for presence of nickel: A few drops of 1% solution of dimethylgloxime (DGM) and a few drops of ammonia water on the jewelry will form a harmless strawberry-red deposit in presence of nickel.

ear nut - Tapped nut for use with ear screws.

earring - An ornament, often of button, clip or pendant shape, attached to the lobe of the ear by a small screw or clip, or by a wire piercing the ear.

ear-screw - An ear-wire with the screw to clamp earrings to unpierced ears.

earth amber - Slightly altered amber which has been exposed to the air and become somewhat opaque and dark and lost some of its luster. Often this surrounds a nucleus of still unaltered amber, but eventually the amber disintegrates completely under these conditions.

earth stone - In speaking of amber this is the mined material, as opposed to the amber washed on the beaches (sea stone). It has an opaque rind which must be removed by sand and water in a rotating washer before the quality of the piece may be seen.

ear-wire - A bow of wire, looped to fasten to a pierced ear, for hanging the pendant portion of earrings or eardrops. Eastern Standard Time. See STANDARD TIME.

ebauche - (ay'boshe) Term used in Swiss watch manufacturing to denote a watch movement with its principal parts assembled, but not yet finished; pivot holes drilled but not yet jeweled; i.e., a movement "in the rough." Comparatively few, but large factories make Ebauche movements, which are bought by hundreds of firms, who place their own names or brands on them, after completing them in various grades of finish, jewelling and adjustment. This system saves the majority of Swiss manufacturers from needing heavy machinery in their shops, in which much of the work is therefore skilled handwork. Another result is that there are rather few basic models of Swiss watches, which is a convenience in ordering repair parts for them. Material dealers furnish customers with charts for identifying the ebauche model of any Swiss movement.

Ebonite - Vulcanized rubber, used for tool-handles, pulleys, and to some extent for black mourning jewelry.

ebullition - (ebb'uh-lish"-un) Formation of gas bubbles by acid applied in precious metals testing, or in an acid bath for chemical reduction of metals.

ecaille - (ay'kye) On European-made articles means genuine tortoise shell.

eccentric - The form given to edge of cams such as the heart-piece that governs the return to zero of hands of chronograph and split-seconds watches; or, anything out-of-center.

eddy current - In electrical timepieces, a current moving in a circular path opposite to the main current due to magnetic influences.

edge joint - In jewelry making, a joint made by filing the edges of the pieces to be joined, at angles to form faces usually soldered together.

egeran - (egg'er-on) A variety of vesuvianite from Bohemia, named for the Eger river.

egg-and-dart - A classic design-element used in moldings for clock cases and in gallery-strip for making jewelry.

egg pearl - Egg-shaped pearl.

Egyptian alabaster - Variety of beautifully banded calcite, found near Thebes. Also called oriental alabaster, onyx marble, onyx and onychites.

Egyptian jasper - Yellow, yellow-brown, chestnut brown and red jasper from Egypt.

Egyptian pebble - Jasper pebbles, commonly polished by the sand blown by the desert winds and which, when sectioned, reveal scenic patterns in browns and grays that are suggestive of landscapes.

Egyptian peridot - Peridot from the principal occurrence, St. John's Island, in the Red Sea.

Egyptian shell - Deep rose pearl shell from the Red Sea, marketed in Alexandria.

Egyptian turquoise - Turquoise from the oldest known mines, in the Sinai Peninsula. Also sold as Alessandrine turquoise.

EI - Abbreviation for "excessively included." See CLARITY GRADE.

eight-day timepiece
- A clock or watch designed to run one week after winding. The extra day's run is included so the clock will not stop if rewinding is delayed; also so that the minimum power of a mainspring at the end of its run is not used in driving the train.

eight-screw chuck - Lathe chuck for large work; holds work inside a pipe through which four pairs of screws are adjusted against the piece of work. See BOX CHUCK.

eight side brilliant - Modified form of brilliant with 33 facets; a table, 8 five-sided and 8 three-sided facets on the crown, 16 three-sided on the pavilion.

eighteen facet brilliant - Form of brilliant cut. See SINGLE CUT.

Eilat stone - A rock composed of malachite, chrysocola and related copper minerals found near Eilat in Israel, in the area of the ancient copper mines of King Solomon.

elaeolite - (e-lee'o-lite) A variety of nepheline; a sodium aluminum silicate. Translucent gray, bluish-green, brown or red, sometimes cut as a decorative material, occasionally it can be cut to show a cat's-eye. Rarely used, and of little value.

Elasticity - A property that underlies the effectiveness of all forms of springs. This is the tendency of a body to return to its original shape after having been deformed, as in bending.

Elbaite - Tourmaline is now regarded as a mineral group, like the garnets, rather than a single mineral. Elbaite is the lithia-containing variety; the usually light-hued gemmy tourmaline crystals in red, green and blue are all elbaites.

elder pith - The pith used by watchmakers for cleaning pivots, etc., obtained from branches of a shrub or small tree of genus Sambucus, the common elder of Europe.

electric clocks - Clocks with hands driven by electric motors through reducing gear trains; or with mainsprings or weights wound by electric motors; or with pendulums given impulse by an armature of an electro-magnet. See MAINS CLOCK: SELF-WINDING; SYNCHRONOUS CLOCK.

electric pickler - Electrically heated pickle pot; eliminates need for open flame in heating pickle. See PICKLE.

- A liquid crystal display in timepieces, in which the bars, when stimulated electrically, assume a predetermined color. Selection of color depends upon which of several magnetic powders is suspended in the liquid in the display.

Electrode - In electroplating, the article being plated, and the piece of metal to supply the coating, while both are immersed in the solution with electric current flowing through them, are the electrodes. See ANODE; CATHODE.

Electroformer - Self-contained electroplating outfit. Used to compensate for casting shrinkages by electrodeposition of metal onto the models.

Electroforming - A process for creating articles of silver or gold that are light in weight although often massive in appearance; developed by B. J. S. Electro-Plating Co., Ltd., of London in late 1960's. A negative mold, fitted with electrical contacts, is placed into a specially prepared silver or gold bath; the metal builds up on the inside of the mold to any desired thickness, preserving intricate surface detail. The technique also permits the creation of minutely exact reproductions. The crown made in 1969 for the investiture of Charles, Prince of Wales, was electroformed. In another electro-forming process, a leaf, bud, butterfly, free-form sculpture or designer's model is covered with pure gold, after which the model is dissolved.

electro-gilding - Electroplating with pure gold. See ELECTROPLATING.

electrolabrum - A candelabrum wired for electric lighting.

electrolyte - A substance conducting electricity and undergoing decomposition in a solution when an electric current passes through it.

electrolytic copper
- A highly refined variety of copper, produced by electrolysis, used for alloying the precious metals.

electroplating - Process of covering metal articles with a film of other metals. The article is immersed in a chemical solution; electric current (D.C.) flows through solution from a piece of metal (anode) to article (cathode), depositing metal thereon by electrolysis. See ANODE; CATHODE.

electrum - An alloy of 20 per cent gold and 80 per cent silver.

element - A substance which cannot be decomposed chemically into other simpler substances; one of 104 known substances, which in various combinations compose all other substances. Gold, carbon (diamond), silver,
copper are examples of elemental substances.

Elie ruby - Misnomer for pyrope garnet found in small grains in trap rock at Kincraig Point, near Elie, Fifeshire, Scotland.

elinvar - An alloy of steel, nickel and chromium, used for hairsprings which yield a timekeeping rate practically without temperature error. The word is coined form "elasticity invariable".

Elster pearl - Pearl from a freshwater mussel from the Elster river in Saxony.

elutriation - (ee-loo'tre-ay"shun) Process for grading abrasive powders by settling and pouring off liquid in which they are mixed. See DECANTATION.

embossing - Art of producing figures in relief, by means of punches and hammers used on the back of metal or with a snarling iron and hammers used on the inside of a hollow article such as a pitcher, coffee pot or a cup, creating the design on the front. See CHASING. 2. Stationery. A design or monogram that is raised or pushed up so that it is in relief. It is not colored or inked.

emerada – Misleading trade name for yellow-green synthetic spinel.

emerald - A green variety of beryl, the color of which is caused by chromium or vanadium. Some foreign gemologists restrict the term "emerald" to stones colored green by chromium. One of the most valuable of all stones. See BAHIA EMERALD; BERYL; BARAKETH; CANUTILLOS; COLOMBIAN EMERALD.

emerald cut - Name given to one of the principal types of facet cutting, the other is brilliant cut. In this cutting, commonly used on emeralds, the elongation of the rectangular facets is parallel to the girdle. The finished stone tends to be square or rectangular. See SQUARE CUT; STEP CUT; TRAP CUT.

emerald filter - A piece of colored glass which passes only a band of reddish light and a band of yellow-green light. Genuine emeralds, demantoids and some green zircons look pink to red through this filter, other stories look green. The filter is also useful in the distinction of other gems. Also called berylloscope, Chelsea filter, detectoscope, etc.

emerald prong - A prong setting having the four corner posts flattened off instead of a 90 degree angle. This actually makes an octagon shape outline commonly referred to as emerald shape.

emerald triplet - Misnomer for an assembled gem made to imitate an emerald. Now most commonly made of two layers of quartz with an intermediate layer of green cement, sometimes made with beryl and the cement. emeraldine. Misleading name for chalcedony which has been dyed green.

emeralite, emeraldite - Misleading name for light green tourmaline from Mesa Grande, Calif.

emer - A commonly used abrasive material consisting of a naturally occurring mixture of corundum and magnetite, the magnetic oxide of iron. See CORUNDUM; EMERY PAPER.

- Hand-buffs, made of wood of various forms, covered with emery paper of grades from coarse to fine, used for operations similar to filing, for polishing, etc.

emery paper, or cloth - Stiff paper or cloth coated with various grades of emery grains glued on, used for grinding and polishing, either as it is, or with the paper or cloth glued to wood or metal laps or buffs; grade-numbers are from 0000, the finest, through 000, 00, 0, then 1 to 4, which is the coarsest.

emery wheels, files, countersinks - Abrasive tools of forms indicated, made of emery grains mixed with binding substance and molded into form.

emulsion - Liquid in which a fatty substance is suspended in minute globules; many watch-cleaning solutions should be emulsions, and should be stirred violently in combining the ingredients; the omission of this is what sometimes produces solutions that give poor results in use.

enamel - A medium used for decorative and other work on jewelry, watch dials, etc. Two principal types of enamel are: (1) hard enamel, a glass-like material in powder form melted on the work; (2) soft enamel, which is in liquid form to be painted on the work; this dries by evaporation or is baked hard in an oven. See LIMOGES.

enamel dial
- Dial for a timepiece made of white or tinted hard enamel fused on a copper plate, with numerals of dark pigment fired into the enamel background. See ENAMEL.

end-grain lap - A flat wood polishing lap usually of boxwood, cut across grain so that the lap surface presents the end-grain to the work; usually used with Vienna lime in alcohol as the abrasive.

endless screw escapement
- A form of escapement using a "worm" screw and fan driven by the train, used in music boxes, and tried at times by manufacturers of watches without success.

end mill - A rotary cutter for making flat-bottomed recesses, used in a lathe or drill press.

endoscope - (en'do-skope) An instrument used in the examination of the interior of the drill hole of a pearl. Its use permits the rapid distinction of natural and cultured pearls.

endpiece - Tapered slide made of brass and set with endstone, for lower balance pivot bearing, in English lever watches.

endshake - The play of an arbor permitted between its shoulders and their bearings in a watch or clock plate, or between endstones and the tops of conical pivots.

endstone - An unpierced piece of stone set over a hole-jewel, for an endbearing to limit the end-shake of a conical pivot; a cap-jewel.

Endura emerald - Misleading trade name for an imitation emerald.

engagement ring - Ring given by a man to a woman as a pledge of marriage. The practice dates from Roman times, but early Christianity transformed the betrothal ring into the wedding ring. The custom of a separate engagement ring was established in the 19th Century, and the present widespread tradition of setting the engagement ring with one or more diamonds resulted from the larger supply of diamonds following their discovery in South Africa in 1866. Matching sets of engagement ring and wedding ring have become increasingly popular in this century. See WEDDING RING.

engaging friction - The friction in gearing that occurs between a wheel tooth and a pinion leaf, before this action passes the line of centers. See CENTERS, LINE OF; DISENGAGING FRICTION.

engine-gauge unit - An aviation instrument that combines on one dial the indications of the oil and fuel pressures, and a thermometer for the cooling-liquid temperature.

engine lathe - Type of turning lathe in which the cutting tool is mounted on a slide, moved by a lead-screw rotated by gearing connected with the lathe spindle. The "screw-cutting" attachment for a watchmakers lathe converts it from a hand-lathe into an engine lathe.

engine-turning - A form of decoration for silverware, watch cases, jewelry, etc., composed of engraved lines, produced on a special lathe with a reciprocating cutter.

English brilliant - Said to be a modified brilliant with 17 crown and 13 pavilion facets.

English escapement - The detached lever escapement in which the escape wheel teeth are of angular form without club-tooth lifting faces; the lifts are performed by particularly sharp points on the teeth.

English finish - A bright highly polished finish on gold, produced by electrogilding, on work previously given a high polish.


English red - Finely powdered hematite used as a polishing material.


English round cut brilliant - A type of diamond cutting in vogue in England in the middle of the 19th Century. It resembles the modern American cut except that the stone was cut for depth, rather than spread, and the depth was the same as the diameter of the girdle. The crown of the stone was cut high to reflect directly as much light as possible, increasing the brilliance in this way, but decreasing the spread. See TRIPLE CUT BRILLIANT.


English size - A system of designation of the diameters of watch movements followed in America and England. A 10-size movement measures \% inches, and the difference per "size," larger or smaller, is 1/30 of an inch. Below 1-size, the diminishing sizes are denoted by naughts: 0 size, 00 size, and so on. See WATCH SIZES.


English square cut brilliant - An early type of cutting with 16 crown facets, an octagonal table and 12 pavilion facets, plus culet. The symmetrical grouping of the crown facets is a step beyond the cuttings that until then had been in vogue. See DOUBLE CUT.


engraver's ball - An iron ball, resting in a ring-pad, with clamp to hold a wood block on which work being engraved or chased is held by cement; the simplest form of engraving block.


engraver's cement - For holding irregularly shaped work to wood block while being engraved; the most used recipe is equal parts of rosin and
brick dust melted together.


engraving - 1. The art of cutting designs in any substance; in the jewelry trades, particularly lettering, monograms or decorations in articles made of the precious metals. 2. Stationery. The process by which a design or lettering is cut in the surface of a metal die. Ink is put into the depressions. Then the paper is forced into the depressions by means of a counter plate. This leaves a raised, inked impression.


engraving block - A heavy metal turntable with clamps for holding work being engraved.


engraving machine - A device that reduces, by means of a pantographic attachment, letters or designs and engraves them on metal. Such machines are made to cut in two or three dimensions. See ENGRAVING; PANTOGRAPH.


engraving pad - A leather pad filled with sand, on which to hold work being engraved. It is still used for work that cannot be clamped in an engraving block; but formerly was used for all engravers' work.


enhydros - (en-hy'dross) A term applied to chalcedony nodules partly filled with water, with movable bubbles often seen in curio collections. Though mentioned in most gem books, they have little or no gem use. Most are from Uruguay.


enstatite - (en'sta-tite) A member of the pyroxene group, a magnesium silicate. It occurs in crystalline masses and may be used as a decorative stone; translucent greenish pieces might be cut cabochon for use as an unusual, sometimes chatoyant, gem. It may rarely be clear and dark green, like diopside. Small crystals were found in the blue-ground in South Africa and were sold under the name green garnet. Larger but poorer crystals are reported from Mogok. See BASTITE.


entering pallet - Term sometimes used for receiving pallet, or "R" pallet, on which an escape wheel tooth first acts as it passes through the escapement. On either pallet, the corner first contacted by a tooth is sometimes called the entering corner. See EXIT PALLET.


entering tap - A screw thread tap with part of the bottom threads tapered, used for starting a tapped hole, to be followed by using a "second" or "bottoming" tap.


eosite - An aventurine-like quartz from Central Asia.


epaulet cut - A fancy diamond shape; in outline, a low isosceles triangle with the two sharp angles truncated by short, parallel facets.


ephemeris - A table of the daily positions of the sun, moon, planets, and certain of the stars, used in taking transit observations for obtaining correct time.


epiasterism - (e'pee-as"ter-ism) Asterism seen by reflected light, as in a star stone. See ASTERISM, DIASTERISM.


epicyclic gear - Gearing in which one wheel travels outside or inside of another which has a fixed axis as used in some tourbillon or revolving-escapement watches.


epicycloid - (epp-i-sie'kloyd) A curve traced by a point on the circumference of a circle as it rolls around the circumference of another circle. The epicycloid is used for the profile of addenda of teeth in gears used in horology. See ADDENDUM; CYCLOID.


epidote - (eh'pih-dote) A silicate of calcium, aluminum and iron. It occurs in many localities in prismatic dark green, strongly pleo-chroic green and brown crystals, but is usually so deep in color that it is unsuitable for gem use. Light yellow green masses, with pink feldspar are sometimes cabochon cut for local sale, under the name UNAKITE. Epidosite is a similar mixture of quartz and epidote. See also PIEDMONTITE; PISTACITE; ZOISITE; THULITE.


epilame - A stearic acid type of treatment of watch parts and plates to prevent the spreading of oil applied later.


Eppler fine cut - See EUROPEAN CUT.


epoxy - Any of several resin compounds having strong adhesion, toughness and chemical resistance, used as coatings and adhesives. Sometimes used as a low-cost substitute for enameling.


equaling file - A thin file with faces and edges parallel, for dressing the edges of a joint to be soldered in a ring, and for similar uses.


equarrissoir - (aye'quarr'i-swoyr") Swiss or French broach, either for cutting or polishing.


equidistant escapement, or escapement with equidistant lockings - A design-type of detached lever escapement in which both locking faces of the pallets are planted equally distant from their center of motion at the pallet center. See CIRCULAR PALLET.


erinide - Trade name for yellowish-green synthetic spinel. See EMERADA.


error, barometric - A timekeeping variation in pendulums caused by changes of atmospheric pressure. The greater the pressure, the shorter are the arcs of motion of the pendulum, with a consequent effect on the timekeeping rate of the clock. In astronomical clocks, the pendulum runs in a controlled partial vacuum, to minimize this error. Ordinary clocks have pendulum bobs made of lenticular or double-convex form, to minimize this error.


error, circular - A timekeeping variation in pendulums due to the varying arcs of motion, minimized by designing clock escapements to permit the shortest possible arcs of pendulum motion.


error, temperature - In watches a variation of timekeeping rate, caused by the effects of changes of atmospheric temperature, principally on the hairspring; and compensated for by using a bimetallic balance. In clocks, a variation of timekeeping rate caused by lengthening of the pendulum rod in heat and its shortening in cold; compensated for by employing various forms of compensating pendulums.


escalloped - Having an edge like the shell of a scallop.


escapement - The mechanism that transfers power in a timepiece from the train to the balance or pendulum. See DETACHED; FRICTIONAL; also specific names of escapements of all kinds.


escapement files - Hand files, smaller than needle files used by jewelers and watchmakers. Generally made with one-piece square handles. Lengths of cuts vary from 34" to 2%" and cuts from #0 to #8, the finest. See FILE.


escapement matching - Adjusting escapements so acting parts work together with maximum mechanical efficiency. "Matching" is a term used particularly in watch factories; in repair shops the term mostly used is escapement "adjusting."


escape pinion - A pinion on the arbor that carries the escape wheel, in a watch or clock.


escape wheel - Toothed wheel in escapement; the last member of the train and the first member of the escapement. Teeth of escape wheel press against a pallet, indirectly imparting motion through it to balance; or directly, through an impulse arm or lip on the balance.


esclavage - (ess'klah'vaj1) Necklace of evenly spaced strands joined at a certain distance from the clasp.

esmeralda - Misnomer for green tourmaline from Haddam, Conn.

essence - In European horological literature, a term often used meaning petroleum distillates such as gasoline, naphtha, etc.

essence d'Orient - (ess'ons-doe'ree-awn1) French term for the fish scale preparation used in the manufacture of imitation pearls.

estrellada - (ess-tray-ya'da) Brazilian term for the deposits in which the diamonds are found.

etching - Process for producing designs on metal by using acid. The design is scratched through a coating of wax or varnish on the article, exposing surfaces of the metal, and acid is applied to eat into the metal to form the design in etching; the acid cannot attack surfaces where the wax was undisturbed. See PHOTO-ETCHING.

eternity ring - A narrow band of platinum or gold set with a full or half circlet of diamonds and perhaps also colored stones, given by husband to wife as a pledge of continued love, to mark the birth of a child, or a wedding anniversary. Custom began in England in 1930's, spread to America in mid-1970's. Earlier, similar styles had been known in America as guard, caliber or insert rings.

Ether - A liquid composed of carbon, hydrogen and oxygen, sometimes used in cleaning complicated watches. It is very volatile and inflammable, so must be kept covered as much as possible and any flame kept away from its fumes.

ethyl alcohol - The variety of alcohol commonly called "grain" alcohol, used either pure or denatured for various processes in watch and jewelry work; as distinguished from methyl or "wood" alcohol.

euclase - (you'klayz) A rare beryllium aluminum silicate which is found in Brazil with the topaz crystals of Ouro Preto in pale bluish, bluish green, to colorless monoclinic crystals which have occasionally been cut as gems. A pronounced cleavage makes it a fragile stone, of interest only to collectors. Crystals from other localities have not been suitable for cutting.

European cut - Term sometimes applied to the Eppler fine cut, a brilliant-cut calculated in 1940 by Dr. W. Fr. Eppler: girdle diameter 100%, table diameter 56%, crown depth 14.4%, pavilion depth 43.2%, crown facet angle 33° 12', pavilion facet angle 40°48'. Diamonds thus proportioned have a bit wider table and a bit shallower crown than do American cut or Ideal cut brilliants. See AMERICAN CUT; SCAN. D.N. STANDARD CUT; EPPLER, W. FR., DR.; OLD-EUROPEAN CUT.

eutectic - (you-teck'tick) An alloy so compounded that its melting point is lower than any combination of its component metals.

euxenite - (youx'en-ite) A mineral composed of many of the rare elements; niobium, titanium, yttrium, erbium, cerium, and uranium. It is black and very heavy. Some pieces have been cut as black gems, for which it is well suited, but they will rarely be seen in the trade. It is one of a group of minerals containing these elements, which with some others, are known as the rare earths. Similar minerals include samarskite, gadolinite, allanite, fergusonite, poly erase.

evening emerald - Misnomer for chrysolite or peridot.

exhaust-fan system - A vacuum fan and pipe system, used in jewelry shops for carrying off and saving wastes from polishing machinery, from which the precious metals may be recovered. Another purpose is to aid the health of workmen by keeping the air in shops free from polishing dust.

exit pallet - Term sometimes used for let-off or L pallet, on which an escape wheel tooth last acts as it passes through the escapement. On either pallet, the corner last contacted by a tooth is sometimes called the exit corner.

expander - A punch and die used for stretching the web and arms of a wheel, to true it or to increase its diameter.

expansion balance - Term occasionally used for a bimetallic balance. See COMPENSATING BALANCE.

external thread - Among varieties of screw threads, a thread cut on the outside of a cylinder; a male thread.

extra facet - A facet on a polished diamond that has been added to remove a natural or other minor surface blemish. Very tiny extra facets do not impair a diamond's clarity grade, but larger ones do so.

eye - Jewelry. An item of findings comprising a ring attached to a base to be soldered to a piece of jewelry that is worn as a pendant, or a chain connection.

eye agate - A banded agate cut so that the bands are concentric and make a dark eye in the center. See CYCLOPS AGATE; OWL-EYE AGATE.

eye glass - A magnifying lens or set of lenses, mounted in a holder worn over the eye, used by watchmakers, engravers and jewelers; also called LOUPE.


face - 1. Crystallography. One of the plane surfaces characteristic of a crystal. 2. Gem-cutting. A term used in brillianteering for a group of facets, all that can be made in a single setting in the dop, two star facets and four halves in the crown, or four halves in the pavilion. 3. Horology. Term occasionally used meaning the dial of a timepiece.

faceplate - A disc mounted on a chuck for a live-center lathe, the edge of disc slotted to hold the tail of a carrier or dog that is clamped on a piece of work held between centers of lathe, this carrier imparting motion to the work while being turned or for other operations. See UNIVERSAL FACEPLATE.

facet - A smooth face, usually, and always when referring to a gem, a polished surface. See CUTTING; POLISHING, etc.

faceted or facet cut - A gem which is bounded by plane faces, as opposed to a rounded cabochon cut.

faceting - 1. The process of putting facets on a gem; also slightly changing the angle of a facet. 2. In jewelry, see FACETING MACHINE.

faceting machine - A machine which, by means of diamond tools and automatic dividing apparatus, permits a limitless variety of highly polished designs, geometric patterns, decorations and lines to be cut into articles of jewelry. Invented in Switzerland in 1962; adopted in the U.S. two years later. Popular machines of this type are known by trade names Tousdiamant and Posalux. 2. An automatic device for cutting stones.

faceting tool - A device for holding work on which facets are to be formed by pressure against the face of a rotating abrasive lap; used by jewelers for metal work and by lapidaries for stones. The tool comprises a base, supporting a spindle with dividing disc and latch on one end and a work-holding clamp on the other end; the disc is latched in successive positions to hold the work as facets are ground or polished on it

face wheel
- Term occasionally used for the minute wheel in the dial train.

facing - In lathe work, the operation of turning or grinding in which a shoulder or surface is cut at or nearly at a right angle to the axis of the lathe spindle.

Fahrenheit - A scale for thermometers in which the freezing point is marked at 32° above zero; the boiling point at 212°; and the space between is divided into 180 equal parts or degrees. See CENTIGRADE.

fairy stone - Fanciful name given to the twinned staurolite crystals which form a perfect cross. Found in Virginia, New Mexico and elsewhere, they are often marketed under this name; usually their surfaces are smoothed before selling. Many imitations are made and sold as genuine.

falcon's eye - Colorless quartz containing parallel inclusions of fine blue needles of crocidolite, which, when cabochon-cut, shows a chatoyance.

fall - Term used by some horological writers to denote angular amount of motion of escape wheel between let off of one tooth and next locking of another tooth. A more commonly used word for this is drop. See DROP.

falling-ball clock - A type of clock popular in the Seventeenth Century, suspended from a bracket or a ceiling, in which the weight of the clock itself unwinds a cord wrapped on the barrel, to drive the mechanism, which is contained inside a ball forming the clock case. The dial numerals are usually around the equator of the ballcase, and turn under a stationary pointer representing the hand of a cupid or similar figure.

false cleavage - Parting.

false lapis - Another name for LAZULITE, also used for DYED AGATE or JASPER.

false plate - Horol. A plate with feet or pillars that fit into a clock movement and upon which the dial is secured.

family ring - Ring with a number of stones, each representing a child, grandchild or other relative.

fancy color diamond - Any gem diamond not included in the usual commercial color ranges of whites, light yellows and light browns.

fancy gallery - An item of jewelry findings, comprising strips of metal for making settings for cameos, etc., with design units of any other form than in "plain" or "beaded" gallery.

fancy pearl - Strongly colored natural pearl.


fancy sapphires - Corundum gems of any color except blue or red.

fancy shape diamond -A diamond cut otherwise than round-as baquette, barrel, bullet, calf's head, crescent, cut corner triangle, emerald-cut, epaulet, fan, half moon, hexagon, keystone, kite, lozenge, marquise, navette, pentagon, square, trapeze, triangle, star, etc.


fancy star - A square 18-facet diamond cutting, with top and bottom alike with a square table and 8 triangular flanking facets.


fan-shape cut - A form of gem-cutting resembling a partly-opened fan, or a segment of a half-circle.


fashioning - All the processes of cutting and shaping through which a piece of rough goes in preparation for jewelry use.


fast rate - A timekeeping rate that shows a gain over correct time.


Fathometer - A gauge to measure the depth in water, used in testing the impermeability of deepsea divers' watches.


fault - Gems. Anything which damages the appearance and thus lessens the value—flaws, scratches, chips, etc.


faultless - Synonymous with perfect or flawless in description of a diamond; subject to FTC regulation. See PERFECT.


feather - Name given to an irregular crack-like flaw in a stone, or a grayish vein (faisel), often seen in twinned diamonds.


feather edge - 1. Silver. A decoration used on the handles of spoons and forks. It indicates a suggestion of feathers repeated along the edge of the handles. 2. Metal work. A burr left on a corner of metal work after cutting, as in gear cutting, filing, drilling, turning and many other similar operations.


feed bridle - The metallic strap in an electric watch connecting the energy source to the electrical parts.


fei-ts'ut - A name originally given by the Chinese to the opaque, brilliant green jade, also known as kingfisher jade, because of the resemblance to the color of the feathers of that bird. Today it means all varieties of jadeite except the opaque dark green. See PI YU; MAW SIT SIT; CHLOROMELANITE.


feldspar - A group of rock-making aluminum silicate minerals with potash, soda and lime. There are some gem forms such as amazon-stone, moonstone, labradorite, and peristerite, but the mineral is one of the most common and a constituent of almost all igneous rocks such as granite and basalt. See ADULARIA; ALBITE; AMAZONITE; AVENTURINE; LABRADORITE; LARVIKITE; MICRO-CLINE; OLIGOCLASE; ORTHOCLASE; SUNSTONE.

feldspar-apyre - French term for ANDALUSITE.

felspar - A British spelling for feldspar, originating
either through a misprint in an old English mineralogy or a mistranslation of the original German, but now, gradually, being phased out.

Felt wheel - Polishing wheels of varying shapes and hardness used for smoothing work.

female - 1. Mechanics. Term denoting hollowed out, as a female lathe-center, with a v-shaped countersink to support a pointed end on a piece of work; or a female stem, with a hollow square to fit the square of a winding arbor. 2. A recessed or open portion of a two-piece die. 3. Gems. The attribution of femininity to a stone usually signifies that it is of weaker color than the male counterpart. Such usage has, of course, no standing and no significance. See MALE.

- Name given to a black iron slag proposed for gem use in Germany; said to take a good polish and make a brilliant stone.

ferrule - 1. A band of metal, fitted to an article made of another substance, as a tobacco pipe, file handle, etc. 2. An adjustable small pulley used on hand lathes.

fesse - (fess') A term in heraldry to designate a broad band of metal or color which crosses the shield horizontally and upon which other charges are occasionally engraved.

fezels - (fay'zels) Wispy, irregular white inclusions inside a diamond that was cut from a made; frequently confined to a twin plane, they reflect grain changes. Also called twinning or knot lines, they are common in pear shapes and marquises, which are often cut from macles.

field effect liquid crystal - A type of liquid crystal display used in some solid-state timepieces; electrical stimulus causes the molecules in selected numeral segments to align themselves in a manner that prevents the passage of light; the digits appear opaque on a light background.

field, magnetic - The region around a magnet in which its influence is appreciable; particularly, in horology, in which magnetism is strong enough to magnetize a watch.

figure-eight caliper - Tool for holding watch balances or wheels for testing during truing operations.

figure stones - Agalmatolite, in reference to its frequent utilization by the Chinese in inexpensive carvings.

file - A hand-tool for cutting metal, etc., to shape it; usually made of steel, with teeth cut by a chisel to cover its surface, then hardened. Files are of many forms, shapes, sizes and degrees of "cut" or fineness of teeth. For special uses in horology, small files are occasionally made of hard stone, like sapphire, ground to shape with surfaces left more or less rough to form cutting teeth. Common shapes of files are: round, half round, 3 square or triangular, pillar, barrette, crossing, equaling, slitting, square, warding, knife-edge and joint. See NEEDLE FILES.

file card - A brush with steel wire bristles, for cleaning teeth of files from metal waste or dirt; effective for course-toothed files, but not for fine-cut files, for which a metal-edged file cleaner is superior. See FILE CLEANER.

file cleaner - A narrow strip of brass or copper, first rubbed across its end against the single-cut teeth near the tang of the file to be cleaned, then the teeth thereby cut in it are pushed across all the teeth of the file, pushing
out dirt and metal waste.

filigree - Jewelry. Ornamental work formed of wire, bent into designs, sometimes with bits of metal added, soldered together and to other parts of the piece of work.

filing block - A block, usually of hard wood, held in a bench vise, its top grooved to support a metal pin while being filed for watch or jewelry work.

filing fixture - A watchmakers' lathe attachment, for filing flat-faced divided work on material held in lathe chuck; it supports a hand file on two hardened steel rollers adjustable in height, to guide the file and control the amount of material being cut.

filing pin - A wooden extension on front of jeweler's bench, for supporting work to be filed or sawed.

filings - Precious metal wastes swept from jewelers' work benches, comprising grains from filing and sawing, small bits of metal cuttings, etc., usually the most valuable class of material for refining to recover metals in usable form; distinguished from the less valuable floor sweepings.

fillet - 1. A narrow strip of metal raised above the general level of a surface, such as the seat for the regulator-index on balance cock of some watches. 2. In silverware, the bands, decorative molding or rims applied to various parts of hollowware pieces. Often used between more important molding.

fillister head - On a screw, as a watch pillar-screw, a head with its edge formed like a vertical wall instead of like the sharp edge of a roundhead screw.

findings - Jewelry. More or less standardized parts of jewelry marketed for use in manufacturing and repair work, such as pintongs, joints, catches, drops, balls, settings, etc.

fine cleavage - Diamond fragments still worthy of cutting after the cleaving. Also used for odd-shaped or flawed stones requiring cleaving.

fine gold - Pure gold of 24 karat quality, without alloy.

fine silver - Pure silver; the silver without alloy.

finger-piece - A button protruding from any part of a watch-case, to operate setting work, a over correct time.


fining - In polishing metal goods prior to electroplating, a light polishing with a dry buff free from the usual abrasive; the rotating buff may be touched occasionally with a piece of charcoal or pumice stone, to keep its surface from becoming glazed.

finish - 1. One of the two principal considerations in determining the cutting grade of a diamond, the other being proportion. The American Gem Society says: "Ideal finish for the round brilliant-cut diamond consists of the uniform and symmetrical placement of 58 highly polished facets . . . with the lower girdle facets extending 13/16 of the distance from the girdle to the culet, with a smooth (though not necessarily polished) girdle perpendicular to the girdle plane and just thick enough to resist chipping, with no apparent variation in the thickness of similar parts of the girdle, and with crown facets aligned exactly with corresponding pavilion facets." Finish faults include extra, misaligned or distorted facets, rough or wavy girdle, and polishing marks. Some diamond-grading systems define most of these factors as symmetry details, and consider finish to mean external observations in clarity grading. 2. Jewelry. See TEXTURED FINISH.

finishing - 1. In watch factories, the operations involving hand work, such as adjusting, as distinguished from production of parts, are classified as finishing. 2. The general term applied to the various processes of polishing silver and jewelry.

finishing stone - A piece of flint stone used by electroplaters for dressing felt polishing buffs, to keep their surfaces in good working condition.

fire - Gemology. The rainbow flashes of light reflected from within a stone. Fire depends upon the dispersion of the gem as well as upon the color and the cutting. In diamond, fire comes mostly from light emerging from the crown facets. See DISPERSION.

fire agate - 1. Glass. 2. The name given to a variety of chalcedony encasing iridescent iron oxide (limonite) which gives something of the impression of an opal.

fire-coat - A film of oxide on surfaces of metal or gem stones, caused by heating work during soldering, etc. Firecoating is prevented by coating work before heating with a chemical antioxidizer, such as boracic acid dissolved in alcohol, followed by immersion in diluted sulphuric acid after the soldering is done. See PICKLING, HEAT SHIELD.

fire marble - A variety of marble in which fossils have been so well preserved that the mother-of-pearl of their shells still gives off the colored flashes characteristic of fresh shell. Also known as LUMACHELLE, AMMOLITE.

fire opal - A reddish Mexican opal, often facet-cut, and not necessarily showing the color play characteristic of other precious opals. A popular and erroneous usage makes this term synonymous with precious opal. See GIRASOL; GOLD OPAL.

fire scale - Discoloration of copper alloys when heated in air. In the case of sterling silver this discoloration is extremely difficult to remove. See FIRE-COAT.

fire skin - Oxidation upon the surface of a diamond, caused by overheating. Repolishing is usually possible with minor loss in weight, unless the stone was dirty, oily and greasy and thus became pitted from the heat.

firing - In "hard" enameling, the heating of articles engraved or otherwise prepared and filled with pulverized enamel, to melt the enamel.

firm-joint caliper - A caliper in which the joint of the arms is fitted with enough friction to hold the arms in place for use after setting.

first bye - An early color-grading term applied to the finest quality of bye or byewater diamonds.

fishbone casting
- A quick method of reproducing a piece of jewelry by casting in a mold made of two pieces of cuttle-fish bone. This bone has, inside of its hard outer layer, a porous substance. Two pieces of this, flattened and keyed together with pins, are pressed together onto the piece of work that is the pattern, until they meet, leaving the form of the pattern pressed into the porous bone, half of it in each piece of bone. Separating the bone, removing the pattern, cutting a "gate" for pouring the metal into the mold, and replacing the two halves of the mold together, leaves it ready to use for casting. Any work that has no undercuts in its form can be reproduced by casting with this fishbone. See CUTTLEFISH BONE.

fish-eye - In reference to diamonds, a stone with a dark ring where the pavilion facets reflect the girdle, because those facets are too flat. Fisheye has also been used as a synonym for moonstone.

fishline cord - Braided silk cord in graded sizes for stringing pearls, etc., for necklaces.

fish pearl - Misnomer for an imitation pearl made from a fish-scale product. See IMITATION PEARL.

fishtail - A method of diamond setting as well as the name for certain settings themselves. In setting a row of diamonds the fish tail is formed by having the holding prongs curved toward each other. Two prongs are formed by splitting a single center post to hold adjacent diamonds. The curving of the metal to the side leaves a notch in the center giving the appearance of a fish's tail, hence the name. Also any individual diamond setting whose prongs have a similar curving effect.

fissure - Diamond grading. An elongated cavity, usually the result of a cleavage opening to the surface.

fitter - A ring turned out of metal, the outside of which fits the movement recess in a watch case, and the inside fitting a watch movement smaller than the case was originally made for.

five-minute repeater - A striking watch which indicates time by strokes, each of which means a five-minute period after the hour or quarter hour last passed.

five-position adjustment - Adjustment of a watch to obtain the maximum uniformity of timekeeping in the positions known as; pendant up; pendant right; pendent left; dial up, and dial down.


FL - Abbreviation for FLAWLESS.

flame fusion - One of the methods of stone synthesis, in this case it is a synonym for the Verneuil process; and is used to make a dis¬tinction between the Verneuil process and the crystallization from a melt (FLUX FUSION).


flame-guard - A protector for stones set in a piece of jewelry from flame used in soldering during repairing. A guard much used is wet thin paper wrapped around parts of a ring, for example, that do not need exposure to the flame.

flank - The non-acting part of a gear wheel tooth. See DEDENDUM.

flannel buff - A variety of polishing lathe buff, made of many layers of cotton flannel of circular shape, stitched together; used for producing a high bright polish with rouge.

flash fire opal - Precious opal in which the color flashes are in rows or streaks, or single broad flashes of color.

flat buff - A hand buff with a long flat abrasive surface, used by jewelers and watchmakers for grinding and polishing.

flat chasing - A surface decoration accomplished by working upon the outer surface of a piece of silver, with a blunt edged tool, which does not, as engraving, cut away any silver but merely displaces and depresses it along the lines of the pattern. See CHASING.

flat ends - Thin diamond cleavages.

flat-face chuck - Design of wire chuck for watchmaker's lathe, with exposed ends of jaws flattened instead of rounded, to bring the strain of holding work more nearly inside the spindle throat. This advantage is somewhat offset by lack of the clearance afforded by the rounded jaw faces of the standard form.

flat-face mallet - Wooden jewelers' mallet for purposes except those for which a forming mallet is used. See FORMING MALLET.

flat graver - Form of engravers' tool for producing a cut with a flat bottom in a plane parallel with the surface of the work.

flat hairspring - A balance spring without over coil; with all of its coils in the same place. See BALANCE SPRING; BREGUET HAIRSPRING.

flat-nose - A variety of pliers with jaws flat-faced inside, with rectangular tips.

flat - A thin, but cutable, rough diamond; one of the five basic categories into which gem quality rough is sorted.

flat drill - Form of drill of earlier origin than modern twist drill, still used by watchmakers for accurate small work like re-pivoting. See DRILL.

flat saw blades - Blades for frame-saws, of oblong cross-section; distinguished from "square" saw-blades which are of square cross section. Flat blades are used for sawing lines of great length with little or no curvature.

flat stock - Flat metal produced by successive passes through rolling mill to reduce its thickness.


flat top - A gem cut with a single table facet for the crown.


flaw - Gems. An imperfection, visible through a ten-power loupe. See INCLUSION.

flawless - The top clarity grade in diamond, generally preferred to the older term "perfect"; restricted by the U.S. Federal Trade Commission 1957 definition of the latter to stones that disclose no blemishes or imperfections of any sort when examined in normal daylight, or its equivalent, by a trained eye under a 10-power, corrected diamond eye loupe or other equal magnifier. American Gem Society: A diamond which discloses no internal or external marks or blemishes, when examined by a skilled person employing a binocular microscope with 10-power magnification and dark-field illumination [certain naturals on the girdle and minor growth lines excepted]. Scan. D.N.: A diamond in which a qualified observer, under favorable lighting conditions, cannot find internal characteristics (inclusions or other inhomogenities) and/or surface finish faults (insignificant cutting-faults or minor surface blemishes) by thorough examination with a 10 x magnifying lens, corrected for chromatic and spherical aberration [certain minor naturals and growth lines excepted]. National Association of Goldsmiths, London: Completely transparent and free from internal inclusions and surface marks when examined by a skilled observer with normal or corrected to normal vision in daylight or its equivalent with a 10-power lens corrected for chromatic and spherical aberration. See PERFECT; INTERNALLY FLAWLESS.

flecbes d'amour - (flesh'dah'moor’) Rutile needles through quartz; "Cupid's darts," rutilated quartz, love's arrows, Venus' hairstone and sagenitic quartz are all synonyms for this material.

flexible bracelet - Bracelet composed of links hinged together to make the whole flexible, used largely for diamond-set jewelry.

flexible extension bracelet - A type of bracelet used for watches or jewelry, with links actuated by springs which allow for extension.

flexible shaft machine
- A machine consisting of a flexible shaft, driven by a motor, attached to a hand piece and operated by a rheostat. Various types of hand piece are used to hold drills, burs, grinding and polishing attachments. The rotary power may be converted to operate a small pneumatic hammer.

flinders diamond - Misnomer for a variety of topaz, from Tasmania.

flinque - Hand engraving covered by transparent colored enamel.

flint glass - A high index lead crystal glass used in imitation gems.

flip-flop circuit - An electronic circuit which, like a see-saw, can assume two positions. Upon receiving an electrical impulse, it switches rapidly from one position to the other. For this reason, the electronic flip-flop is widely used in electronic watches to convert precisely-timed pulses from a quartz crystal into voltage or current pulses that can drive the watch's frequency-dividing circuits. Most common are integrated-circuit flip-flops, made in tiny chips of silicon, a semi-conductor material.

flip leaf clock - A type of carriage clock made in U.S.A. (Ansonia), France and Germany with digital display using stacked cards which are flipped every minute to reveal the time.

flirt - Horol. A lever rotating on an arbor, for suddenly actuating a mechanism at intervals, such as on the last arbor of the independent train in an independent centre-seconds watch; or in some chime clocks to act on the quarter rack hook every 15 minutes.

floating balance - A balance suspended by its helical hairspring and guided by a wire through the hollow staff of the balance. Such hairsprings have one half of their helix clockwise, the other half anti-clockwise to keep the balance on an even plane.

floating dial - Light, usually plastic dial taking the place of hands and moving with the cannon pinion, hour wheel and fourth wheel pivot.

floating opal - Opal chips in glycerin, enclosed in a glass sphere. Similar baubles containing chips of various colored stones have come on the market, i.e., floating emeralds, floating rubies, floating amethyst, etc.

floating stud - A hairspring stud that is clamped in place by a screw or plate, the stud freely entering a socket in the balance cock so that the spring itself places the stud in position before it is fastened, avoiding risk of bending the over-coil during assembling, and aiding in uniformity of attachment of spring under repeated removals and replacements.

Florentine finish - A textured surface for precious metal produced by engraving a series of parallel lines in one direction, then cross-hatching them at a 90° angle more lightly than in the first direction. The work is done by a flat graver that cuts a series of lines; such tools come in several widths and spacings.

florentining tools - Lining gravers used in obtaining Florentine finishes.

flower stone or flower agate - A variety of agate with branching plumose markings, often of one color tipped by another, found in Oregon. Also known as plume agate.

flue scratch brush - A form of metal-bristled scratch brush used by jewelers for work inside of openings of small diameter.

fluid friction - The friction inherent in liquid or semi-liquid substances produced by their component molecules rubbing on each other. In horology, as a lubricant thickens by evaporation, its fluid friction increases, eventually requiring its removal by cleaning the mechanism, to allow application of fresh lubricant.

fluorescence - (flew"or-ess'sense) An unexplained light phenomenon, the property possessed by some substances of changing and reflecting invisible ultra-violet rays as longer visible wave-lengths of light. Diamonds often fluoresce blue, willemite is usually a brilliant green under the ultra-violet rays.

fluoric acid - Term sometimes used for hydrofluoric acid, used for etching enamels, glass, and some soft gemstones.

fluorite - Calcium fluorite, colorless when pure, but usually attractively colored by various, probably organic, impurities. It is a common associate of the metal ores, is 4 on the hardness scale, forms cubic and octahedral crystals and has an octahedral cleavage. It very often fluoresces and the phenomenon has received its name from this mineral. It is not suitable for use as a gem, but is often cut and sold under the names blue John, false-amethyst, -emerald, -ruby, -sapphire and -topaz. Stores selling Chinese carved objects usually sell it under the name "green quartz." See also CHLOROPHANE; CABRA STONE; DERBYSHIRE SPAR; LITHO LAZULI, etc.

flush - Term used to denote a condition when a surface of one part, such as the top of a jewel setting, is made to lie in the same plane as another part does, such as the surface of the watch plate into which the jewel setting is fitted.

flushed-solder findings - Jewelry findings with bases coated with solder for convenience in quickly attaching to work. See FINDINGS.

flux - A substance used to promote fusion by preventing oxidation at the point of soldering, thus enabling the solder to flow. In soldering gold and silver, a solution of borax is used as is a commercial preparation known as "Self Pickling Flux." For soft soldering, common fluxes are zinc chloride, ammonium chloride, hydrochloric acid and tallow. There is on the market a so-called platinum flux but, since platinum does not oxidize, no flux is necessary.

flux fusion - A common method of gemstone synthesis, involving a molten compound in which are dissolved the ingredients for the desired stone, such as emerald, YAG, ruby, and the like. A cooler level allows them to crystallize out in the upper region, after dissolving near the bottom of the platinum pot. It is the method used by Chatham and Gilson, among others.

fly - 1. The last pinion of the striking train with vane attached, used as speed governor for the striking train of a clock. 2. A fan for checking the momentum of escape wheel in Dennison gravity escapement for tower clocks and regulators.

fly-back - Descriptive term, or mechanism, concerning chronograph watches in which a sweep-second hand, after being stopped to time an event, is returned to zero by pressing a button. Modern chronographs were first called "start-stop-and-fly-back" watches, to distinguish them from the earlier timers that were started and stopped by moving a lever, but that had no fly-back provision.

fob - A short chain, ribbon or other similar thing, fastened to a watch to aid in withdrawing it from a pocket in clothing.

focal length - In an eye loupe, the distance from the lens to the sharply defined object.

foil - 1. A Gothic term for the intersecting point at the junctions of circular areas, as in trefoil, quatrefoil, and cinquefoil. 2. A leaf of very thin metal. 3. A thin leaf of silvered and tinted copper employed by jewelers to give color or brilliancy to pastes and inferior stones. 4. A thin coat of tin, amalgamaged with quicksilver, applied to glass, to cause reflection.

foil backed - Gems which have had their backs covered to increase their brilliance, in the case of colorless gems such as Baroda gems (glass), or to improve their color as is very commonly done in older settings of pinked topaz, pale amethyst, etc.

folder - A bench machine for turning up a hem on the edge of a piece of sheet metal, to form a tubular receptacle as for the hinge of a joint, etc.

foliot - A straight bar of metal, set horizontally on balance staff or earlier verge escapement time-pieces, bisected by the staff, and serving as the balance in these clocks and watches. See VERGE ESCAPEMENT.

follower - 1. A term sometimes used for the gear wheel that is turned by another wheel or pinion. 2. In a verge escapement watch, the brass plug that holds the hearing for the outer pivot of the escape wheel pinion.

fool's gold - Popular name of iron pyrite; it is often mistaken for gold, but is hard and brittle, where gold is soft and malleable.

foot - 1. A projection from a part of a watch or clock, to provide fastening to some other part; as a dial foot, which is usually a short piece of copper wire that passes through a hole in the lower plate of a watch, and is fastened to the plate by a screw or a pin. 2. The potance, or lower balance cock, under the upper plate of fullplate watch. 3. One of several bases on which some types of hollow ware are mounted. See FULL PLATE.


foot blower - A bellows for generating air pressure for gas blast to heat jewelers' melting furnaces, muffle furnaces for hardening steel, or for torches for soldering.


foot control - An electrical rheostat operated by foot, for varying the speeds of a watchmakers' lathe motor and flexible shaft machines.


foot-jewel - The lower hole, or cap, jewel in a watch or carriage clock.


foot wheel - Foot treadle and heavy, grooved wheel used to power tools before electrical motors.


forging - Shaping metal by heating it and hammering it into form, with hand hammers or in a die-press.


fork - 1. Horology. In a lever escapement, the acting end of the lever-arm that is a part of the pallet, and through which power is applied to the roller jewel at each impulse to the balance. The fork comprises the slot or notch, the horns, and the guard point or guard pin. 2. Silversmithing. A tined instrument used at the table for manipulating food, introduced into England, from Italy, early in the 17th Century. Crude servicing forks had been used several centuries earlier in England. Individual place pieces include dinner, fish, ice cream, luncheon, oyster or cocktail, and salad or pastry forks. Serving pieces include asparagus; bacon; cold meat or buffet; lemon; olive or pickle; and salad forks.


fork-action angle - In lever escapement, the angular amount of motion of lever and fork, between the bankings.


fork-and-roller action - In a lever escapement, the mechanism, and its action, pertaining to the application of power to the balance, comprising the fork and its horns, the guard pin or point, the bankings, the impulse roller and roller jewel and safety roller in double roller escapements, or the roller and roller jewel in single roller escapement.

fork horns - Wing-shaped projections on both sides of the fork slot in a lever escapement. The front edges of the horns provide safety-action to retain the fork on the proper side of the escapement, during the passage of the roller jewel through fork action, when the normal safety action by the guard point and roller edge is absent. If the lever is jarred away from the banking at this time, safety is effected by contact of the edge of horn with front of roller jewel, which prevents passing of the fork over to the wrong side of the escapement. See FORK.

fork slot - The notch in fork of lever escapement, in which the roller jewel acts alternately to unlock the escapement and to receive power for impulse to the balance. See FORK.

fork-slot gage - A set of plug gages numbered for matching roller jewels to fork slots.

formation striation - The curving bands often seen in the synthetic corundum gems have been called this.

former roll - A tool, sometimes fastened on a bench, with three steel rollers for shaping sheet metal into curved forms.

forming cutter - A lathe turning tool with cutting edge formed like the complete profile of the work to be produced; an example is a graver with rounded point to shape the curved profile of the base of a "conical" pivot.

forming mallet - A mallet with its head shaped for indenting sheet metal; sometimes used in operations on work for which there is not a suitable sink in the dapping block. See DAPPING; DIE.

forsterite - The magnesia end-member of the magnesium iron silicate group of rock-making minerals called chrysolite, olivine or peridot. Red Sea peridots are much nearer to forsterite than they are to the pure iron member of the series, fayalite; fayalite and forsterite seem to mix in any proportions to make the minerals of the olivine group.

fortification agate - Agate cut to show zigzag angular lines, resembling the fortification outlines of an old map.

fountain oiler - A device for applying oil to watch parts, comprising an oil reservoir which forms the handle, on one end of which is a fine tube like a hypodermic needle, through which oil flows to the work.

four C's - Catch phrase coined to encompass the quality and value considerations of a diamond: COLOR; CUT; CLARITY; CARAT WEIGHT.


four-hundred day clock - A mantel clock with torsion pendulum, driven by mainspring or electro magnet and dry battery, and running for a year or more without rewinding or replacing battery. The torsion ("twisting") pendulum is a horizontally rotating weight suspended on a thin steel ribbon; the period of oscillation is very long in time, so that the great intervals between escapement impulses uses the power very slowly, which is the principle that produces the year-long running of the clock.


four-legged gravity escapement - A variety of the Dennison gravity escapement used mostly in tower clocks. See GRAVITY ESCAPEMENT.


four-point diamond - 1. A brilliant oriented in the cutting to place the table parallel to the cube direction. 2. A diamond weighing four points, or four one-hundredths of a carat. (0.04 ct.).


fourth wheel - The wheel in most watches that drives the escape-wheel pinion; its pinion has a long pivot that passes through the watch dial and carries the second hand. It makes one turn per minute.


foxtail chain - Chain used for stringing necklace beads and other purposes in jewelry work, braided of fine wire, the chain itself of small diameter.


fowlerite - A variety of rhodonite found in New Jersey, containing zinc, and sometimes cut as a local gem.


fracture - The manner of breaking, when speaking of minerals. Fractures may be splintery, as in satin spar, or conchoidal, as in quartz, or uneven, as in beryl, b. Diamond clarity grading. A curved or irregular separation inside a diamond, with a splintery, uneven appearance; distinguished from a cleavage, because not planar.


fraise, Ingold - A device for correcting the profiles and finish of gear wheel teeth, used in repair work, and in manufacturing high-grade watches in Switzerland; named for the inventor, Pierre F. Ingold.


frame - 1. In a watch or clock, the structure of plates, bridges and cocks that contains the pivot bearings for the acting parts of the movements, outside their cases, during regulating.


framesite - Aggregates of diamond, carbon and bort, found in the Premier mine.


fraser - A small tool made of steel used by stone setters on a drill press, flexible shaft machine or rotating handle to enlarge surface-drilled holes, or to give holes which have been drilled, different surface shapes.


Frederician cut - A cabochon cut stone with one or two rows of facets around the edge. Often used on chrysoprase.


free arc - The portion of the motion of a balance during which there is no contact between any part of balance and any part of escapement.


freedom, corner - In lever escapement adjusting the play between the corner of the fork-slot and the front of the roller jewel, in the safety action during the time when the jewel is passing through fork-and-roller action.


freedom, guard - In lever escapement adjusting, the play between guard point, or guard pin, and the safety-roller edge.

free spring - A balance spring without provision for regulation by curb pins. Marine chronometers, and occasionally very fine watches, have no curb-pin regulators; in them regulation is effected by meantime screws in the balance rim.

French chalk - Mineral talc finely pulverized and decanted to use as a polishing abrasive. See DECANTATION.

French clock - In the U.S.A., a term used to classify a type of clocks made in France. Characteristics of these clocks are brass plates highly polished; pinions cut from solid steel; Brocot pendulum suspension; mainsprings fully enclosed in barrels; pin-pallet escapement; manufacture organized as subdivided handwork, so repair parts must be fitted from rough material or made outright; cases of stone, glass-paneled in gilt framework, bronze, ormolu gilt, etc., artistic in design and finely finished.

French color rubies - Lighter than blood red stones.

French cut - A square, mixed cut stone with a square table turned at 45 degrees to the outline of the stone. The crown is normally brilliant cut, but the pavilion may be either step or brilliant cut. See MIXED CUT.

French measurement - A system of linear measurement, based upon the ancient Paris foot; one ligne is one-twelfth of the inch, which is one-twelfth of the Paris foot. Swiss watch movement diameters are mostly measured in lignes. See DOUZIEME; LIGNE.

French polish
- Shellac dissolved in alcohol, some¬times having color added, used as a varnish for clock cases, jewelry or silverware boxes, etc.

Fremy rubies - Misnomer for synthetic rubies made by the French chemist, Edmond Fremy (1814-94), by a chemical reaction process which involved heated aluminum fluoride and which resulted in the formation of small but very well formed crystals. Some of these were cut and were known as "scientific rubies."

frequency - The rate per unit of time of the oscillations of an alternating electric current. A frequency of 60 cycles per second is mostly used in current for synchronous motor electric clocks.

fresh water pearls - Pearls from a mussel living in fresh water, of the genus Unio. The shells have a very fine luster and have been extensively used. Some very fine pearls have been found during the fishing operations. From time to time, ill-informed advertisers have used the term misleadingly to denote imitation pearls.

fret - An ornamental part of a clock case, with a design in sawed pierced-work, usually fastened above the hood of the case, made of thin wood or metal.

fret saw - A saw for cutting fretwork. See SAWFRAME.


fret-work - Angular interlaced ornamentation, used sometimes in borders of silver articles.

friction - An effect produced when two surfaces are caused to slide on each other. Friction resists motion, consumes power, produces wear on the sliding surfaces. It may be minimized by selection of materials for sliding parts of mechanism, polishing the surfaces lubrication. See ENGAGING FRICTION; DISENGAGING FRICTION; FLUID FRICTION; ROLLING FRICTION; SLIDING FRICTION.

frictional escapement - One of a class of timepiece escapements in which the part that applies power (impulse) to the balance, remains in frictional contact with some part of the moving balance during practically its entire vibration in each direction, as in the verge, cylinder and duplex escapements. The opposite principle is embodied in "detached" escapements, in which the impulse-applying part is held free from contact with any part of the balance during nearly its entire vibration in each direction. See CYLINDER ESCAPEMENT; DETACHED ESCAPEMENT; DUPLEX ESCAPEMENT; VERGE ESCAPEMENT.

frictional-rest escapement - See FRICTIONAL ESCAPEMENT.

friction jewelling - Jeweled bearings for pivots in watches, in which the jewels are pressed friction-tight into framework of the movement, instead of being set by burnishing metal over the edge of the jewel.

friction plating - Process of gold or silver plating, by rubbing a metal surface with a wad of cloth or cotton, wetted with a chemical paste containing the metallic element to be coated on the work. Used for silvering timepiece dials, for patching worn spots on plated work, etc.

friction staff - A type of balance staff for watches, in which the staff is fastened to balance by a friction-fit in a hole in a hub on balance, instead of being riveted into a hole in the balance arm.

friction-tight - Term meaning fitting a part on another by a tight fit that requires considerable force to put together or separate the parts.

friendship jewelry - Bracelets, rings, etc., on which are hung bangles given by the wearer's friends, engraved with their names or initials. See BANGLE:

friendship ring - A type of band favored by teenagers after World War II, usually of carved sterling silver or gold filled and 5 mm. wide.

Friesland clock - A type of clock originated in Friesland province of the Netherlands, usually made to hang on a wall, with an ornate hood covering the movement, and the weights and pendulum hanging exposed.

frieze - In the designing of some clock cases, an ornamental band between a cornice above and a part below that usually rests on columns or pilasters.

frit - Enamel in chunk form before grinding. See ENAMEL.

frost agate - A fanciful name given to a gray chalcedony with white markings within the stone resembling snowflakes or patches of snow.

frosting - A type of finish on metals, consisting of a myriad of small pits in the metal surface, produced by sandblasting, steel-bristled brushes, grinding on a lap with coarse abrasive, or chemical action. Varieties of frosting are used as finishes on watch parts, jewelry and silverware. 2. Glass. Glass is frosted by acid; by applying an abrasive to which powdered glass sticks; or by sand-blasting.

frothy amber - A chalky white opaque amber.

fuchsite - A green chromium-colored mica which colors the common green aventurine quartz, in which it often occurs. See CHROME MICA; COPPER MICA.

Fukien jade - Misnomer for brown soapstone.

fulcrum - The point of support for the action of a lever. Pivots of train gear wheels, of pallet arbor, of balance staff, etc., act as fulcrums of levers in timepieces.

full-cut brilliant - A girdled or round diamond on which 58 facets have been cut. Besides table and culet, these are: 4 top corner, 4 bottom corner, 4 bezel or top main, 4 pavilion or bottom main, 8 star, 16 top half or break, 16 bottom half or break. See definitions for each of these facets. See also AMERICAN CUT; EUROPEAN CUT; SCAN. D.N. STANDARD CUT; SINGLE-CUT; GIRDLING; BLOCKING; BRILLIANTEERING.

full-Dutch rose cut - See FULL-HOLLAND ROSE CUT.

full-head - On a watch movement case screw, a head left completely circular instead of with a segment cut away. See DOG-SCREW.

full-Holland rose cut
- Cutting style consisting of circular girdle, flat, unfaceted base, and pointed crown with 24 triangular facets.


full-plate - A design for watch movement in which an upper plate covers the entire train and holds the bearings for all of its upper pivots; the balance cock and balance are superimposed over the plate.

fully adjusted - Term applied legally when a watch is adjusted to isochronism, temperatures and all usable positions.

funeral ring - These were usually made of gold and date back to the Colonial period. They were presented to pallbearers. See FUNERAL SPOONS; MOURNING JEWELRY.

fusing point - The temperature at which a substance melts.

fusion metal - Metal with silver on one side and copper on the other, or copper with silver on both sides, from which old Sheffield plate was manufactured.

futuran - A synthetic phenol aldehyde plastic used in imitations of amber. See BAKELITE.

fuzee (or fusee) - (fue-zee1) A device in timepieces for equalizing the power applied from the mainspring to the train, invented by Jacob Zech of Prague in 1525. It consists of a brass cone with a spiral groove cut on it, in which is wrapped a chain or cord, with one end fastened to the mainspring barrel. The spring unwinds the chain from the fuzee on to the barrel, turning the fuzee, on which is the first gear wheel or main wheel of the train. With the spring fully wound, at its greatest strength, the chain is pulled from the groove at the least diameter of the fuzee, with the shortest radial leverage; as the spring runs down, it pulls the chain from a gradually increasing radius of the fuzee, which increases the power effect to compensate for the lessening power of the spring. The fuzee is seldom used today in watches; but was considered necessary in marine chronometers.

fuzee chain - A tiny metal block chain with a hook at each end; one end being connected to a toothless barrel and the other end to the base of the fuzee wheel. Invented by A. Gruet of Geneva, Switzerland, ca. 1664.

fuzee engine - Lathe used to cut the tapered, helical groove in a fuzee blank.

fuzee stopwork - An extension on the watch plate interrupting the last turn of the fuzee when nearing full-wind.


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