diamond specs
Fred, how important is the big three angles 34.5%, 40.75%, and 43% to the cut of the diamond. Most "ideal" cuts I find are spot on these numbers. Would I be ok with say 35%, 40.6, and 42.5% on a 61.1 depth and 56 table XXX diamond that is SI2?
Hi Daniella,
Great questions!
Q1) Pavilion angles and crown angles are critical in the proportions of a diamond!! Pretend they are two of the four tires on a car. No one tire is more important than the other. The third number you mentioned (43%) is a pavilion depth percentage. You pointed out a wonderful point: "most ideal cuts are spot on with these numbers". More than 3/4 of rounds diamonds on the market are cut poorly to savage weight! How can so many diamonds ironically have the same crown and pavilion angles? The answer is pretty disturbing. It's grade bumping! Just take a look at the majority of lab grading reports out there on the market. It seems as though they all pretty much have the same proportions. BIG RED FLAG! Labs are doing one or both of these things: 1) picking the best case scenario within the 8 crown angles and 8 pavilion angles and/or 2) using a few pre-made templates for proportions for all diamonds. Either one of these scenarios represents proportions incorrectly. The best practice in varying proportions is to ask for a Sarin/Megascope report--NOT lab report!
Q2) Based on the numbers you presented, I'm assuming we're dealing with a round diamond. 61.1% is not an acceptable depth percentage for a well-proportioned diamond. (See http://www.diamondcuttersintl.com/61/) Total depth percentage beyond 61.0% is a symptom of other things gone wrong. If you ask for full Sarin/Megasope report, you'll definitely see the problematic area(s). The clarity SI2 and the proportions you mentioned do not have a direct correlation. Rule for Class I and II diamonds are consistent for all clarities.
Have a great day!
