Crown angle and pavillion angle

[atldc]

What crown angle and pavillion percentage should I be looking for on a very well cut princess cut diamond sarin report?

 

[Paul-Antwerp]

Like in rounds, the light performance is a result of the crown-pavilion-combo. Because rounds are traditionally cut in a very tight range, you see little deviation from certain angles.

In princess-cuts, this is entirely different. You will find extremely few good combos, and it is necessary to examine the whole combo. In this case, it encompasses 2 pavilion angles, and if possible also the details of 2 crown angles. These four angles work together for light performance, and nobody in the know can answer any question without having at least the three most important of the 4 angles.

Live long,

 

[Garry H (Cut Nut)]

I have uploaded a chart that is provided to cutters as a target range for god princess cut proportions (the small red zones).

As Paul says - you can not really do this easily - it is almost impossible to get the second crown angle from Ogi and Sarin scans - only Helium has this level of accuracy - and Helium is not commonly available yet.

So you really are best to rely on ideal-scope and aSET images, as well as DiamCalc and Gem Adviser, at this time.

BTW I deliberately made this file so ppoor that you can not read the data as it is copyrighted. The 3 charts are for different table size ranges in 5% jumps. It is far too difficult to use as a grading system.