GIA cuts and HCA score

[2bogey]

Hi - new member here. I am somewhat confused between the relationship between GIA cut grades and how it scores on the HCA.

For example, say you have a GIA RB 1.50 HVS1, Depth 60.1, Table 58, CA 33, PA 40.8. It gets a "Very Good" cut grade by GIA, but scores 0.8 TIC (excellent) on HCA.

Does 0.8 TIC mean this is an ideal cut? If so, why does it only get a "Very Good" cut grade under GIA???

(Sorry if this has been answered in another post somewhere).

 

[chrono]

I know this has been answered here recently. Off to look for that thread...

 

[JohnQuixote]

Date: 10/17/2007 3:07:36 PM
Author:2bogey
Hi - new member here. I am somewhat confused between the relationship between GIA cut grades and how it scores on the HCA.

For example, say you have a GIA RB 1.50 HVS1, Depth 60.1, Table 58, CA 33, PA 40.8. It gets a ''Very Good'' cut grade by GIA, but scores 0.8 TIC (excellent) on HCA.

Does 0.8 TIC mean this is an ideal cut? If so, why does it only get a ''Very Good'' cut grade under GIA???

(Sorry if this has been answered in another post somewhere).

Welcome to PS 2bogey.

That configuration is at the shallow side of the "commonly agreed-on" top range here, due to the 33 CA. The HCA is centered more on that shallow side so it likes this configuration better than the GIA system, which prefers the steep side. The AGSL cut guidelines predict this combo to be on the border of AGS0 and 1 for light performance (depending on cut precision and other factors).

Chrono may be off to find something more helpful.

 

[chrono]

Still looking...

 

[2bogey]

thanks for the help!