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markboots

Rough_Rock
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Jun 27, 2007
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If you have an ideal cut diamond (by AGS standards) but only VG symmetry and polish is the diamond now a AGS2 or AGS4?

Thanks.
 
Ideal = 0
excellent = 1
I think VG = 2
 
AGS changed the requirements for an AGS0 round brilliant cut grade in 2005 in order to better describe diamond cutting. It’s still quite common for stones to be described as AGS0 when they meet the pre-2005 rules but will not meet the current rules so the selling dealer won’t submit them to AGS for grading. Instead they will use a lab report from someone else for a few of the parameters, a sticker from a Sarin or Ogi machine for a few more and just sort of wing it from there. Even in 2004 this didn’t work very well because of calibration issues but it’s really inappropriate now since AGS no longer uses that system.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
Good point Neil.

Add to my commnt above - if the stone recieves AGS 0 for light return and has no other factors like tilt, gridle thickness etc that would result in a downgrade, then .......
 
In summary, its like golf. low scores win

VG equals 2 over, if you are two strokes back on the 6th and 7th hole, even if you are par on everything else you will, obviously, be 4 over overall.

so 2 on polish and symmetry should make it an AGS4 based on their numerical grading system, though that does seem like a ridiculously steep penalty, especially when compared to GIA excellent cut grades accepting VGs in their top tier.
 
Date: 7/30/2007 12:15:34 AM
Author: WorkingHardforSmallRewards

so 2 on polish and symmetry should make it an AGS4 based on their numerical grading system, though that does seem like a ridiculously steep penalty, especially when compared to GIA excellent cut grades accepting VGs in their top tier.
Click to expand...
Though not sure...I don''t think that''s right. I think you stick with the worst score, in principle. That is...two 2s make for a 2...not a 4 after you add them together...whether or not that applies to this particular stone.
 
Date: 7/30/2007 12:29:25 AM
Author: Regular Guy

Date: 7/30/2007 12:15:34 AM
Author: WorkingHardforSmallRewards

so 2 on polish and symmetry should make it an AGS4 based on their numerical grading system, though that does seem like a ridiculously steep penalty, especially when compared to GIA excellent cut grades accepting VGs in their top tier.
Click to expand...
Though not sure...I don''t think that''s right. I think you stick with the worst score, in principle. That is...two 2s make for a 2...not a 4 after you add them together...whether or not that applies to this particular stone.
Click to expand...
hum, since I have some time, im going to go run some searches and maybe I can find some examples, blue nile here I come!
 
Well, this settles the issue that I was wrong, however, thats mostly because I got myself confused on terminology, was thining the finish and polish/sym was given numbers..anyway, here is an example of VG VG with a cut grade of two

The answer to your question lay here



 
Date: 7/30/2007 12:15:34 AM
Author: WorkingHardforSmallRewards
In summary, its like golf. low scores win


VG equals 2 over, if you are two strokes back on the 6th and 7th hole, even if you are par on everything else you will, obviously, be 4 over overall.


so 2 on polish and symmetry should make it an AGS4 based on their numerical grading system, though that does seem like a ridiculously steep penalty, especially when compared to GIA excellent cut grades accepting VGs in their top tier.
Click to expand...

It’s a demerit system.

Any number of demerits, meaning scores higher than zero, will stay attached to all the way to the end while each attaboy, meaning a zero score, will be forgotten in the summary if even a single demerit is earned. They aren''t cumulative. Ten zeros and a single two will be summarized as a two, as will eleven twos. Golf scoring is much more forgiving in that a sufficiently good or even lucky score on a later hole can offset a bad mark on an earlier one.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver
 
The cut grade has three factors, the lowest of which determines the final grade.

Light Performance is a cumulative grade (added up). It's the sum of all deductions for Brightness, Contrast, Dispersion & Leakage. If the total deductions are
Proportion Factors is part cumulative (girdle thickness, culet size) and part net-lowering (durability, weight ratio, tilt). If the girdle and culet both have deductions of 1 the PF grade is 2. If there are no cum deductions but weight ratio and tilt both have deductions of 1 the PF grade is 1 (b/c those are net-lowering deductions). If there are no deductions the PF grade is 0.

Finish (polish & symmetry) are net-lowering. Polish can be 0 and symmetry can be 2, which would result in a finish grade of 2. Polish and symmetry can both be 2, which would also result in a 2. If the polish grade is 5 and the symmetry grade is 0 the finish grade is a 5.

The cut grade is the lowest grade (net) between LP, PF and Finish.

Light Performance 0
Proportion Factors 0
Finish 1
Cut grade = AGS1

Light Performance 3
Proportion Factors 0
Finish 0
Cut grade = AGS3

Keeping it "real" for the original poster... AGSL is extremely hard on finish, which many elite craftsmen applaud. For the consumer; if you find a diamond that scored 0 in light performance and proportion factors - and the polish/sym is EX or VG (making it AGS1 or AGS2) those differences won't be visible to the naked eye. Such a diamond can be a nice deal if discounted because of this.
 
Date: 7/30/2007 12:31:22 PM
Author: JohnQuixote

The cut grade has three factors, the lowest of which determines the final grade.

Light Performance is a cumulative grade (added up). It''s the sum of all deductions for Brightness, Contrast, Dispersion & Leakage. If the total deductions are < 0.50 the LP grade is 0. If 0.50-1.49 the LP grade is 1. If 1.50-2.49 the LP grade is 2 and so on.

Proportion Factors is part cumulative (girdle thickness, culet size) and part net-lowering (durability, weight ratio, tilt). If the girdle and culet both have deductions of 1 the PF grade is 2. If there are no cum deductions but weight ratio and tilt both have deductions of 1 the PF grade is 1 (b/c those are net-lowering deductions). If there are no deductions the PF grade is 0.

Finish (polish & symmetry) are net-lowering. Polish can be 0 and symmetry can be 2, which would result in a finish grade of 2. Polish and symmetry can both be 2, which would also result in a 2. If the polish grade is 5 and the symmetry grade is 0 the finish grade is a 5.

The cut grade is the lowest grade (net) between LP, PF and Finish.

Light Performance 0
Proportion Factors 0
Finish 1
Cut grade = AGS1

Light Performance 3
Proportion Factors 0
Finish 0
Cut grade = AGS3

Keeping it ''real'' for the original poster... AGSL is extremely hard on finish, which many elite craftsmen applaud. For the consumer; if you find a diamond that scored 0 in light performance and proportion factors - and the polish/sym is EX or VG (making it AGS1 or AGS2) those differences won''t be visible to the naked eye. Such a diamond can be a nice deal if discounted because of this.
Click to expand...
Thanks John.
I knew you would come along sometime with a
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definitive and well explained answer.
 
dang it, I knew all that but got myself confused in my time crunch responding...thanks for the clarification though JQ, people like myself are going to cause confusion
32.gif
 
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