estimating weight of gemstones

Estimating Weight of Gemstones You cannot weigh a gem in a setting and it is rarely worth removing. Instead, you can get a close approximation of the weight by the gem’s volume. In order to use these formulas, your measurements must be e xtremely accurate. Careful observation is also important. All these weights are adjusted by the stones proportions and it takes a trained eye to make those judgments. Round faceted stones: Diameter squared x depth x S.G. x .0018 = carat wt. Oval faceted stones: Length x width x depth x S.G. x .0020 = carat wt. Emerald cut faceted stones: Length x width x depth x S.G. x .0025 = carat wt. Rectangular faceted stones: Length x width x depth x S.G. x .0026 = carat wt. Square cut faceted stones: Length x width x depth x S.G. x .0023 = carat wt. Marquise cut stones, (navette): Length x width x depth x S.G. x .0016 = carat wt. Pear cut stones: Length x width x depth x S.G. x .0018 = carat wt. Square cushions: (average corner meas.& belly meas. for diameter) Diameter squared x depth x S.G. x .0018 = carat wt. Rectangular Cushions: (average L & W for diameter) Diameter squared x depth x S.G. x .0022 = carat wt. Square step cut stones: (average both meas. for diameter) Diameter squared x depth x S.G. x .0023 = carat wt. Rectangular step cut stones: Length x width x depth x S.G. x .0025 = carat wt. Cabochon cut stones: Length x width x depth x S.G. x .0027 = carat wt.

estimating weight of gemstones

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