How does a recently graded AGS000 get a 3.4 on the HCA??

[angeline]

What gives here? Who do I believe? Would this be a good stone or not?

Depth: 62
Table: 55.4
Crown: 34.9
Pav: 41.2

It was graded AGS Ideal 0 this year, but gets a 3.4, VG, G, G, VG on the HCA.

Anyone know why?

Thanks,

a

 

[pricescope]

HCA penalizes for the light leakage. This stone has a bit deep pavilion and can have light leakage under the table.

You can download Gem Adviser (free program with numerous examples) and see this effect on the closest model.

 

[angeline]

Thanks Pricescope! I just don't get how AGS can rate the light performance as Ideal if it might have leakage under the table?

I'll go look up that linky

a

ETA: darn it I just looked and it's only for Windows - I've got a mac

 

[ladyciel]

This table shows the thumbnails for the idealscope images GemScope would produce. They aren''t very big, but you CAN begin to see the lighter/whiter table beginning to appear in the range of crown and pavillion angles for the diamond you listed.

 

[angeline]

Date: 6/18/2007 10:21:46 PM
Author: ladyciel
This table shows the thumbnails for the idealscope images GemScope would produce. They aren''t very big, but you CAN begin to see the lighter/whiter table beginning to appear in the range of crown and pavillion angles for the diamond you listed.

Thanks ladyciel! That was very helpful.

a

 

[oldminer]

AGS is making a "category" which does include a variety of good looking diamonds. Who knows without close personal observation which one you might prefer. You''ll find all AGS 0 diamonds attractive. The question is, Which one do you prefer.

All top quality diamonds, regardless of the system, are not idential or totally equal. There is a range of the best. Some labs have tighter categories and some looser categories. Its personaol preference with a regard to budget and price which control the final decision.

 

[JohnQuixote]

Date: 6/19/2007 8:00:18 AM
Author: oldminer

All top quality diamonds, regardless of the system, are not idential or totally equal. There is a range of the best. Some labs have tighter categories and some looser categories. Its personaol preference with a regard to budget and price which control the final decision.

Precisely.

The HCA, AGA, AGS and GIA all differ slightly but there is strong overlap in recommended/top configurations.

For instance, let''s take preferred pavilion angles: For 53-58% tables, pavilion angles of 40.6-41.0 have the greatest approval cross-system. The AGS cut guidelines cite most candidates for 0 in that range. The HCA and AGA prefer the shallow side (and a bit lower). GIA prefers the steep side (and higher).

The prediction depends on overall configuration of course, but it''s nice that strong overlap exists.