Why are these HCA grafts different?

[coloradorocky]

Why are the GIA and AGS parameters different on these 2 grafts?

 

[coloradorocky]

Other graft.

 

[coloradorocky]

Actual graft.

 

[kenny]

GIA allows a wider range of crown and pavilion angles in their top cut range than AGS does.

Many people feel that the GIA range permits diamonds that are cut too deeply to have the best light performance.
These steep/deep stones allow the cutters to retain more of the rough diamond material, and make more money.
Optimum proportions grinds away more rough material.

This makes me think of AGS is looking out for the consumer and GIA is looking out for the diamond sellers.
This is why I prefer to support AGS by selecting their diamonds over GIAs when possible.

 

[FB.]

One stone has a 55% table and the other 58%. Those different tables will require slightly different other proportions to make an ideal stone.
The GIA cut grade system is less stringent than AGS, which is why the outlines of the lab top grades are different.