Rich- where to find specs on cut classes?

[greta2002]

Rich, you recently explained that cut grades are categorized 1A through 4B. Where can one find how the cut grades are assigned (in terms of tables, pav. and crown depths, etc.)? Thanks!

 

[Richard Sherwood]

There's (3) accepted cut grading systems on the market today. Two only cover round brilliant cuts, the GIA cut grading system (1 thru 4), and the AGS cut grading system (0 thru 10).

The one I prefer is Dave Atlas' AGA cut grading system (1A thru 4B), which is basically a fine tuned extrapolation of the GIA system (forgive me if I over-simplify Dave). The AGA system is also the only one which attempts to rank fancy cuts as well.

You can find the AGA cut grading system described at:
http://www.gemappraisers.com/index.htm

You can find the GIA & AGS cut grading systems described at:
http://www.diamondgrading.com/Articles_GIA_vs_AGS_CUT.htm

 

[JayTee]

Rich,
So if GIA *does* have a cut grading system, why do they not include it on their certificates? I keep reading about how they are working on a new cut grade structure, and how it will be made public very soon, is this the one that you refer to?

Thanks,
JayTee

 

[Richard Sherwood]

Good question, JayTee. I've never quite figured it out myself.

The GIA is composed of (2) components. The GIA school(s), and the GIA Gem Trade Laboratory(s). Sometimes it seems like the two are in different worlds.

I believe the answer to your question is that the cut grading system (which is their old system, not the "new one" they're working on now) was devised by the school, and never adopted by the lab. In other words, it was a system helpful to students in assessing cut, but not something the labs wanted to incorporate into their reports. Supposedly this is because of the great (and deserved) controversy regarding cut, along with the fact that their research was still in "flux".