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Stone Weight Estimation Formula

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This is a guide on how to estimate the approximate weight of a gemstone based on its length to width ratio.

 

Round


    Diamond:
Average diameter² x depth x 0.0061 x weight correction٭

   Color Stone: Average diameter² x depth x S.G. x 0.0018 x weight correction*

 

 

Oval


    Diamond:
Average diameter² x depth x 0.0062 x weight correction٭

   Colored Stone: Average diameter² x depth x S.G. x 0.0020 x weight correction*
                                (use average length and width for diameter)

 

 

Pear


    Diamond:
Length x width x depth x adjustment factor x weight correction٭
       
        Adjustment Factor

Length to width Ratio

Adjustment Factor

1.25:1.00 0.00615

1.50:1.00

0.00600

1.66:1.00

0.00590

2.00:1.00

1.00575

    Colored Stone: Length x width x depth x S.G. x 0.0018 x weight correction*

 

 

Marquise


    Diamond
: Length x width x depth x adjustment factor x weight correction٭

        Adjustment Factor

Length to width Ratio

Adjustment Factor

1.25:1.00 0.00565

2.00:1.00

0.00580

2.50:1.00

0.00585

3.00:1.00

1.00595

       

 

Emerald Cut

 
    Diamond:
Length x width x depth x adjustment factor x weight correction*

        Adjustment Factor

Length to width Ratio

Adjustment Factor

1.00:1.00 0.0080

1.50:1.00

0.0092

2.00:1.00

0.0100

2.50:1.00

0.0106

         

 

Heart


    Diamond:
Length x width x depth x 0.0059 x weight correction٭

    Colored Stone: Length x width x depth x S.G. x 0.0021 x weight correction*

 

 

Triangle


    Diamond:
Length x width x depth x 0.0057 x weight correction٭

    Colored Stone: Length x width x depth x S.G. x 0.0018 x weight correction *

 

 

_________________________________________________________________

 

٭ Weight Correction
   

  • All Cuts: Add between 3% and 8% depending on thickness of the girdle.
                 A high or lumpy crown may require a correction of up to 10%.


  • Oval, Pear, Marquise, Heart: Add up to 10% for wide wings or high shoulders.


  • Step Cuts: Add up to 18% for pavilion bulge.

 

 


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