What are the ideal stats you should have on a GIA or HRD Cert?

[khnglh]

Hello..

Understanding the 4 C is pretty easy but from the information GIA and HRD certs, what are the key factors or stats that will allow one safely guess that the diamond is well cut. Please advice.

Thanks
Khnglh

 

[Giangi]

Hiya!

On a HRD cert, you should look for very good prop. and very good finish grade. HRD does not give excellent or ideal ratings. The best is very good.
HRD lists all %'es, so it will be very easy for you to start avoiding some dogs... As a general rule, the following proportions will look very nice:
Table: 53-57
Crown: 14.5-16
Pav.: 42-43.5
Girdle: thin (2-2.5%) or medium (3-4%)
Obviously, there are a lot of possible combo's and try to avoid the extremes. Numbers are rounded to the nearest 0.5%, so they won't be 100% accurate...

On a GIA, you need to get additional data, as they only list table and depth measurements. Ex/Ex for polish and symmetry is a nice place to start.