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Gemstone Weight Calculation Formulas


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Hereunder the standard formula

 

Round faceted stones: Diameter squared x depth x S.G. x .0018 = ct

Oval faceted stones: Length x width x depth x S.G. x .0020 = ct

Emerald cut faceted stones: Length x width x depth x S.G. x .0025 = ct

Rectangular faceted stones: Length x width x depth x S.G. x .0026 = ct

Square cut faceted stones: Length x width x depth x S.G. x .0023 = ct

Marquise cut stones, (navette): Length x width x depth x S.G. x .0016 = ct

Pear cut stones: Length x width x depth x S.G. x .0018 = ct

Square cushions:

Diameter squared x depth x S.G. x .0018 = ct

Rectangular Cushions:

Diameter squared x depth x S.G. x .0022 = ct

 

Square step cut stones:

Diameter squared x depth x S.G. x .0023 = ct

Rectangular step cut stones: Length x width x depth x S.G. x .0025 = ct Cabochon cut stones:

Length x width x depth x S.G. x .0027 = ct Average corner meas & belly meas for cushions,

L&W for rectangles, etc..

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