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So why is this diamond "Very Good" cut and not Excellent?

crashprime

Rough_Rock
Joined
Jul 16, 2013
Messages
52
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2829789.htm

My understanding of diamonds gets better by the day reading and learning but I guess when you get to the upper echelon, minor variations can affect grading.

I am looking at this diamond from Whiteflash and I am having a hard time understanding why it's getting a grade of "Very Good" for cut, when it falls within the Ideal Table/Crown/Pavilion combination according to http://www.agslab.com/docs/pbcg/AGSLProportionCharts.pdf

What's odd is the Sarin report agrees putting the proportions at "2" Very Good. Is the girdle variance Thin->Slightly Thick (1.5% to 4%) the cause of this?

Is there any concerns with this girdle?

It possesses Ideal Light Performance and Symmetry. Would a polish of "Very Good" really bring the entire cut rating down 2 grades?

Will this diamond have a noticeable performance difference compared to a "Cut Above" AGS000?
 
Re: So why is this diamond "Very Good" cut and not Excellent

I would ask whiteflash...it may be an error on AGS's part...
 
Re: So why is this diamond "Very Good" cut and not Excellent

I am noticing that the certificate for that stone is coming back as invalid on the AGS verification website as well.

http://www.agslab.com/verify_diamond_grading_report.php

Whiteflash is looking into the certificate validation, and any possible discrepancies. Weird.
 
Re: So why is this diamond "Very Good" cut and not Excellent

Because AGSL's cut grade can be only as high as the lowest grade assigned for Light Performance, Symmetry, and Polish.
AGSL report specifies Polish grade 2.
AGSL's (DQD report w/ Light Performance) cut grade is not proportions-dependent - a stone that falls within a certain range may or may not earn the grade specified on the chart depending on PGS (3D ray tracing programme) results.
PGS: http://www.americangemsociety.org/performancegradingso

GIA's final cut grade may be one grade higher than the lowest grade assigned for Symmetry and Polish (assuming proportions earn that cut grade).
 
Re: So why is this diamond "Very Good" cut and not Excellent

Yssie|1375988536|3499148 said:
Because AGSL's cut grade can be only as high as the lowest grade assigned for Light Performance, Symmetry, and Polish.
AGSL report specifies Polish grade 2.
AGSL's (DQD report w/ Light Performance) cut grade is not proportions-dependent - a stone that falls within a certain range may or may not earn the grade specified on the chart depending on PGS (3D ray tracing programme) results.
PGS: http://www.americangemsociety.org/performancegradingso

GIA's final cut grade may be one grade higher than the lowest grade assigned for Symmetry and Polish (assuming proportions earn that cut grade).

This one would seem to disagree with what you're saying.

http://www.agslab.com/pdf_sync_reports/104065427022-PLDQRH.PDF

Light Performance: 0
Polish: 1
Symmetry: 0

Overall: 0
 
Re: So why is this diamond "Very Good" cut and not Excellent

crashprime|1375989081|3499163 said:
Yssie|1375988536|3499148 said:
Because AGSL's cut grade can be only as high as the lowest grade assigned for Light Performance, Symmetry, and Polish.
AGSL report specifies Polish grade 2.
AGSL's (DQD report w/ Light Performance) cut grade is not proportions-dependent - a stone that falls within a certain range may or may not earn the grade specified on the chart depending on PGS (3D ray tracing programme) results.
PGS: http://www.americangemsociety.org/performancegradingso

GIA's final cut grade may be one grade higher than the lowest grade assigned for Symmetry and Polish (assuming proportions earn that cut grade).

This one would seem to disagree with what you're saying.

http://www.agslab.com/pdf_sync_reports/104065427022-PLDQRH.PDF

Light Performance: 0
Polish: 1
Symmetry: 0

Overall: 0

Well, my mistake! Thanks for catching that cashprime - I learnt something today.
http://www.americangemsociety.org/theperformancebasedc-2
(I couldn't find a timestamp on that page though, so I don't know if it's still accurate)
 
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