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Diamond Weight Estimate for Oval Shape

Although the length-to-width ratio is an excellent way to help describe the shape of an oval, it does not apply to its weight estimation formula. Instead, an average diameter must be calculated by dividing the sum of the length and the width by two. This formula is almost identical to the round. Here the LWA multiplier value is .0062 (instead of .0061).

Oval Formula: Average Diameter x Average Diameter x Depth x GTA x Shape Adjustment x .0062

1) Example of formula in use:

Length measurement: 8.06 mm
Width measurement: 5.89 mm
Depth measurement: 3.98 mm
Girdle: Extremely Thick-
Squarish: 1.03

Refer to subsection 11.13. The shape adjustment is a judgment call by the estimator. The more extreme the shape, the higher the multiplier. In this case, the oval has slightly squared shoulders, so a 1.03 adjustment multiplier is in order.

Average diameter: 8.06 + 5.89 = 13.95 divided by 2 = 6.975

Formula will read: 6.98 x 6.98 x 3.98 x 1.07 (GTA) x 1.03 x .0062= 1.325 rounded to 1.32

2) Example of formula in use:

Length measurement: 4.82 mm
Width measurement: 3.02 mm
Depth measurement: 1.92 mm
Girdle: Medium+
Normal Shape: NA

Average diameter: 4.82 + 3.02 = 7.84 divided by 2 = 3.92

Formula will read: 3.92 x 3.92 x 1.92 x 1.015 (GTA) x .0062 = 0.1856 rounded to 0.18

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