Ready to sell your gold OR, are you buying gold? Do you
know the real value - or trust person telling you how much its worth?
Have you ever wondered how much your jewelry or
flatware is worth? Don't have someone to trust to value your precious metal
items and would like to Do-It-Yourself at home but don't know how? Below you
will find up to date gold, silver, and precious metals testing methods. We have
tried to be complete as possible for most common types of jewelry and precious
metals that people own. You will find instructions on testing gold (From 10K to
24K) silver, platinum, palladium, and gold filled. Learn how to quickly and
easily value your products - don't be fooled by the gold buyer at the counter,
you need to know the real value BEFORE you decided to buy or sell!
In the following instructions we will give you the basic knowledge to begin to
practice using testing kits (acid testing). With some patience and more
practice, you will find yourself becoming an expert metals tester. When your
begin, remember not ONLY to rely on your testing equipment, you must use your
eyes to observe the distinct colors, features, trademarks, and other things that
can distinguish real value and precious metal content from surface plating or
fake jewelry. With more experience many people are able to spot something that
stands out on an item that will alert you for the need of careful or repeated
testing before giving a value.
Non-Destructive testing included below can be scratching the piece being tested
against a testing stone or rubbing the surface with a pencil eraser (or light
abrasive pumice or silicone wheel). Although the piece may need some polishing
or cleaning afterwards, non-destructive testing does not penetrate deeply into
Destructive tests are tests where you are using a jewelers file or abrasive
wheel to reach deeper into the metal. If you are trying to maintain original
condition, this may require a jeweler to make repairs afterward (and may
diminish the value of some items).
Using a magnet
Rare earth and powerful magnets can be helpful in checking for base metal
(non-precious metals containing nickel or iron) items. By checking every
lot/item before you start testing, the magnet can save you time because ,most
items attracted by a magnet will not only contain little/no precious metal but
most refiners will not accept them when you want to sell your gold. You will
find that most gold plated and gold filled jewelry and most costume jewelry will
not be attracted to the magnet so to confirm the precious metal content; you
will still have to do one of the testing methods listed in this article.
NOTE: Jewelry clasps on neck chains (trade names: “lobster claws” and “spring
rings”) contain a metal leaf spring inside to function properly so you do not
have to worry if they are attracted to the magnet you can look for a quality
stamp or just go on to further testing.
Items that are slightly attracted to your magnet will require more inspection
and testing. Jewelry that has a heavy rhodium plating (bright silver color) like
on bracelets or charms will show some magnetism to a strong magnet. For heavy
rhodium plated items to be properly checked for precious metal content, you must
get though the surface and do a destructive test (cut deep into the metal).
Apply the 14K acid to the cut. If it bubbles green, the item is not gold or
silver. Rhodium plated items will bubble green so it is important to scrape the
surface clean with a file. If it turns a light milky gray it is at least 90%
silver. If it turns brown with very light green bubbles it is 8K gold or below.
If it just turns brown with no bubbles it is likely 10K gold. If it does not
change color it is likely 14K gold or better. 10K white gold will normally
bubble green when the acid is applied. Test it on the stone to confirm that it
is 10K gold.
Using The Acid Test Kit
WARNING: Use extreme care in handling gold and silver testing solutions and
store in a safe place because they are corrosive acids. In case of skin contact,
flush with large amounts of water - then treat affected area with sodium
bicarbonate or baking soda. If swallowed, contact a physician or hospital at
once. In case of spills, treat with water and then sodium bicarbonate or baking
Testing For Gold
The concept of using
gold testing acids is simply observing a reaction of
the item after the acid is applied. The acid can also reveal the presence of
other materials. When testing with acid, if you are observing green colored
bubbling, you may have an item that has little or no gold content.
The Basic Needle Acid Test Procedure:
Begin by rubbing or scratching the item to be tested directly onto the
surface of the testing stone. Press firmly over an area of 1 to 1.5 inches long
so that it leaves a thick visible deposit. Next, place a scratch line with a
gold test needle next to the scratch line of the metal you are testing. When you
begin to drop on the acid, compare the speed at which the scratches dissolve. If
the test scratch dissolves more quickly than the needle scratch, it is a lower
karat than the needle.
stone thoroughly with water after each use
Testing for 10K, 12K, and 14K Gold
Scratch the gold piece to be tested on the stone (Using the procedure
above). Next to this position, scratch the appropriate needle (10, 12, or 14K).
Place a drop of the appropriate acid on the stone where the gold was rubbed off.
If the gold is the same karat or higher, the color of the scratch mark for the
gold piece will appear the same as the mark from the needle (after 10-15
seconds). If that gold piece is a lower karat (or not gold at all), the
scratched deposit will become fainter and eventually disappear (if there is no
gold content, it will disappear more quickly). If the gold being tested
dissolves very slowly or turns to a yellow-rust or brown color, it is gold that
is under the karat being tested.
Testing for 18K Gold
Scratch the test piece on the stone and apply 18K acid. Any gold that is
less than 18K will disappear in less than 30 seconds. Gold that remains on the
stone is 18K or higher.
Testing for 20K and 24K Gold
Scratch the gold piece on the stone. Next, scratch any item of known karat
(coin or needle) on the stone. Apply one drop of acid (22K or platinum) to the
area. The material that starts to disappear first has the lower karat.
Testing for Gold Filled
Scratch a sharp corner or edge of the item on the stone (this tends to get
through the surface faster than a flat area). Then scratch another strong
streak, from the same edge or corner right next to the first streak. Then do it
a third time, all three next to each other. Apply the same 14K acid to all the
streaks. If the second or third streak fades out or significantly changes color
the piece is heavy gold filled. On most gold filled one streak is all that is
needed. If it fades away completely there is no gold content.
Testing for Platinum
Scratch the test item on the stone and apply one drop (22K or platinum)
testing acid to the application on the stone. If the material is platinum, it
should keep its white, bright color for over 1 minute.
Note: Iron and steel items will pass the stone test for platinum so use a
powerfull magnet to identify these metals. There are plenty of other white
non-magnetic metals that will give false platinum stone readings like metals
used in stainless flatware, some class rings, chromium cobalt, and dental
Testing for White Gold
The same procedure for platinum can be used for 18K white gold. The material
on the stone should start changing to a light bronze color in about three
minutes. For 14K white gold, the material on the stone should disappear in 15
Testing for Silver
Place a drop of acid on the object to be tested.
• 90 to 100% silver, the acid will show a creamy color
• 77-90% silver, the acid turns a gray color
• 65-75% silver, then the acid will show a light green color
NOTE: With the silver solution, it is possible to test directly on the piece
being tested, however, the solution will dull the polishing of the piece, and
leave a mark where the acid was placed.
Testing for Palladium
Rub item on stone and apply 18K or 22K acid. If the metal has palladium
content, the streak will very slowly turn a yellowish green color. If streak
fades completely it is not palladium.
One of the time proven ways to determine karat values is to rub a standard
item (14K ring or 10K class ring, or 22K coin, etc.) on the test stone and your
unknown item next to it. Drop the most applicable test acid on both streaks at
the same time. The weaker will fade first indicating a lower karat. Some people
keep a small 10K and 14K ring as standards for this type of testing.
Invasive / Destructive Tests
If you are not getting results that are clear or comprehensive enough, you
can try further testing using destructive tests. You may consider using a
destructive test in cases where you need to be assured of accuracy, there are
still questions in your mind, the item has little aesthetic value, or it can be
easily repaired. To those who still question beyond this, the only way to
confirm true uniform content of precious metal would be to melt the item
completely down and take a sample testing from the ingot!
There are three ways to test the metal obtained from destructive testing:
• Acid placed directly onto the item
• Testing metal shavings taken from filings
• Using an open area from the item to rub onto the testing stone
Destructive Gold Testing
In destructive testing the investigation begins with the notion that the
item is lower karat or may be of very low karat content (or non-precious metal)
so we start with the lower end of the testing spectrum; 10K. File or grind deep
into the metal with a jeweler’s file or using cutters, you should open the item
so that underlying metal is visible. You may use any of the three testing
methods above (shavings, direct acid on piece, or rub exposed surface on testing
Direct Acid Test: Apply the 14K acid directly on the open cut. On both white and
yellow gold metal, if the cut immediately and profusely bubbles very green, the
item is gold filled or gold plated and the metal is likely copper, nickel or
some brass alloy. If the application of the 14K acid on to the cut or filed flat
surface causes the metal to turn immediately brown but after 10-15 seconds there
are no green bubbles, then the item tested is true 10K gold.
Observation of the green bubbles is best examined with some type of
magnification (like a jeweler’s loupe). You can also observe them by blotting
the acid with a white tissue (The green will be visible on the tissue) If after
10 seconds there are only a few green bubbles the item is likely 9K. If there
are numerous green bubbles after 10 seconds the item is about 8K. If bubbles
appear instantly the item is 7 karat or less. If there are profuse bubbles the
item is 6K or below. Remember: This is applicable only after the streak faded
but not completely with the acid.
Note: 10K white gold will very slightly bubble green when the 14K acid is
applied. This is normal due to the high nickel alloy.
Destructive Silver Testing
File or grind deep into the metal with a jeweler’s file or using cutters.
You should open the item so that underlying metal is visible. You may use any of
the three testing methods above (shavings, direct acid on piece, or rub exposed
surface on testing stone)
Direct Acid Test: Apply the 14K acid directly on the open cut. If the metal is
90% or higher the spot will turn a whitish milky gray color, it will likely
be.925 sterling silver. (FYI: The whiter the color, the higher the silver
content). If the spot turns a noticeably darker gray color the silver is
approximately 80%. (FYI: The darker the color the lower the silver content). If
the silver is below 60% green bubbles will form. If the bubbles are immediate
and very green and profuse the item is not solid silver.