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Culet Chip
As just discussed, the deepest point (A) of the culet chip is taken for the measurement (B). Divide that by the estimated depth percentage. You can then calculate the finished weight with your formula.
If the culet has a large chip out of it, then the same method applies. Take a measurement from the surface of the chipped culet to the table and make a note of it. Subtract another 2/10ths of a millimeter for polishing. Judging from the existing proportions, decide on the depth percentage that would be appropriate. Example: The new depth measurement after the chip has occurred on the culet, is 4.4 millimeters, (4.2 mm to be safe). Since we want to squeeze as much weight as possible (because it is a lower quality stone), we assign a 58% depth percentage: 4.2 mm divided by .58 = 7.24 Now you have the necessary numbers to plug into the formula. The formula will read: 7.24 x 7.24 x 4.20 x .0061 x .98 = 1.316 or 1.31 ct. Remember, the factor .98 discounts 2% for a flat stone. So you have a 1.31 H color I1. Don't forget to include the cutting fees when making your offer.
