Why is this rated only very good?

[johncapecod]

Can anyone point out why this is stone is rated GIA very good cut and not excellent?

1.00 F VS1
6.51 - 6.57 x 3.90mm

Cut VERY GOOD
Polish EXCELLENT
Symmetry VERY GOOD
Fluorescence NONE

Table: 58%
Depth: 59.7%
Crown Angle: 34
Pavilion Angle: 41
Girdle: Thin-Medium (faceted) 2.5%

COMMENTS: cut grade affected by brillianteering

HCA score: 1.3 (excellent in all 3 except scintillation is very good)

 

[Lane03]

I'm guessing due to the brillanteering.

https://www.pricescope.com/community/threads/gia-cut-grade-affected-by-brillianteering.49713/

 

[John P]

I'm guessing due to the brillanteering.

https://www.pricescope.com/community/threads/gia-cut-grade-affected-by-brillianteering.49713/

Precisely. In basic terms this means the upper or lower break facets were indexed and polished-on at slightly steeper or shallower angles than what GIA considers nominal. If deleterious, this causes a reduction in brightness at the edges. In rare cases the diamond may not suffer adverse effects, but we would need a good ASET image to make any kind of judgment about that.

Here's an article I composed on the topic some years ago
https://www.pricescope.com/journal/visible_effects_painting_digging_superideal_diamonds

 

[johncapecod]

Thanks guys! John, I don't have an ASET image but this is what was given to me. It's just a magnification of the stone so I'm not sure if you'll be able to tell anything from it?

To me, the stone sparkles but I compared it to a GIA XXX stone with a perfect H&A pattern and could tell it doesn't quite hold up... but just barely. And only because I can compare both side by side.

When it's mounted how much of a difference is there really?