GIA cut grade vs. HCA score

[leapinghorse]

Hello. One of the stones I came across has a cut ranking of "good" based on the GIA certificate, but scores a 1 HCA. Here are the specs:

Measurements: 7.15 - 7.24 x 4.53 mm

Carat Weight: 1.50

Color Grade: H

Clarity Grade: SI1

Cut Grade: Good

Proportions:

Depth: 63.0 %

Table: 57 %

Crown Angle: 35.5°

Crown Height: 15.5 %

Pavilion Angle: 40.4°

Pavilion Depth: 42.5 %

Star length: 50 %

Lower Half: 80 %

Girdle: Thin to Very Thick, Faceted

Culet: None

Finish:

Polish: Very Good

Symmetry: Very Good

Fluorescence: Medium Blue

Does anything stand out as to why the cut would be ranked relatively low? Is there factors that the HCA does not look at that I must consider?

Thanks again

 

[JulieN]

very thick girdle.

 

[belle]

the highest cut grade a diamond with a ''very thick'' girdle can get from gia is ''good'' it doesn''t matter what anything else is. so, the angles may play out well on hca, and even in real life but gia won''t grade it higher than ''good''.

 

[JohnQuixote]

The HCA and GIA's system are not in agreement on shallow stones. The proportions combination would receive VG as a GIA cut grade (PA 40.4). The main culprit here is the girdle ranging to Very Thick, which knocks it down to G.

Edited to add: Ladies first.

 

[leapinghorse]

Thanks that''s good to know. Should the thin to very thick girdle concern me? Does this have a direct impact on the diamonds "performance"?

 

[JulieN]

you should get an Ideal Scope picture. and it should be priced well.

 

[belle]

Date: 5/7/2007 4:48:07 PM
Author: leapinghorse
Thanks that''s good to know. Should the thin to very thick girdle concern me? Does this have a direct impact on the diamonds ''performance''?

it should concern you in that the stone is facing up much smaller than a 1.5ct. should. so, basically, you are paying a 1.5ct price for a 1.25-1.30ct. size stone.

 

[diamondseeker2006]

Date: 5/7/2007 5:03:26 PM
Author: belle

Date: 5/7/2007 4:48:07 PM
Author: leapinghorse
Thanks that''s good to know. Should the thin to very thick girdle concern me? Does this have a direct impact on the diamonds ''performance''?

it should concern you in that the stone is facing up much smaller than a 1.5ct. should. so, basically, you are paying a 1.5ct price for a 1.25-1.30ct. size stone.

Yep, a 1.5 should have a diameter of around 7.4mm. I wouldn''t even look at one with less than 7.3mm. May as well buy a 1.25 and not pay the premium for the 1.5 weight.

 

[leapinghorse]

Gotcha. It''s going for $8100 FYI. I requested an IS as well.

Thanks again.