Color Grading GIA VS. AGS

[newguy2010]

Hi Everyone,

Another noob question.

This time about color grading.

In general, which is considered the more strict in terms of grading color - GIA or AGS?

 

[yssie]

Experts please correct me if I'm wrong - I believe historically AGS was somewhat harsher, but there were complaints and so they adjusted to be in-line with GIA grading?

 

[stone-cold11]

GIA developed the D-Z color grade, so what they say is the standard, AGS is probably just following whatever trend they noticed in GIA color grading so they will always lag, catchup, lag...etc. be it GIA loosening or tightening the grading.

 

[Lorelei]

Date: 3/9/2010 6:45:38 AM
Author: yssie
Experts please correct me if I''m wrong - I believe historically AGS was somewhat harsher, but there were complaints and so they adjusted to be in-line with GIA grading?

I remember hearing that they were tougher on colour or clarity ( can''t remember which) but maybe one of the experts with recent knowledge of how the two compare can advise.

 

[Stephan]

I saw several diamonds that were graded harsher by GIA than by AGS, for the color.
So I think GIA is stricter for the color.

 

[Paul-Antwerp]

No meaningful difference between the two.

 

[Dancing Fire]

Date: 3/9/2010 10:44:17 AM
Author: QueenMum
I saw several diamonds that were graded harsher by GIA than by AGS, for the color.
So I think GIA is stricter for the color.

agree with QM.my wife''s GIA H is closer to G,her AGS I is closer to J.

what i don''t understand is...what so hard about matching up the color with a master set.

 

[kenny]

Date: 3/9/2010 11:39:02 AM
Author: Dancing Fire

what i don't understand is...what so hard about matching up the color with a master set.

Let me speculate.

Say the color of the stone being graded appears to be exactly between the E and F master stones to every grader that looks at it.
Should they give it an E or an F?
Nature provides stones of a continuous graduation of color that humans force into separate grades.
This is why I feel discrete color grades should be replaced with a continuous number from 1 to 100, just like measuring weight.

Today's D could be the numbers 1 through 4.
E could be 5 through 8, etc.
If four steps in each of today's grades is not enough resolution make it 1 through 1000.
Then each of today's grades would have 40 steps in it.

I've read here that if you lined up several stones of the same grade the heavier ones will show more color.
Let's say all the stones in the master set are 1 carat.
The further the stone being graded is from 1 carat the more imagination is required, especially for those borderline stones.

 

[Tom Gelb]

Hi Kenny,

Having graded many thousands of diamonds for their color it is my belief that the ranges currently used are surely small enough. Many would disagree and that is fine, but please remember that consistency is the hallmark of a good color grader and the smaller the range the harder it is to be consistent.

Also I would suggest that your idea would not solve the question of an in between grade. If a stone was between 8 and 9 or even 101 and 102 what is the actual grade?

Just as an FYI at the GIA and I believe most other labs the master stones are placed at the highest end of a color range so if a diamond is better (has less color) than the F masterstone then it would be graded as an E, if it was better than the E masterstone then it would be a D.

I hope this helps.

 

[kenny]

Date: 3/9/2010 1:42:46 PM
Author: Tom Gelb


Also I would suggest that your idea would not solve the question of an in between grade. If a stone was between 8 and 9 or even 101 and 102 what is the actual grade?

The "actual" grade would be the result of a coin toss, just as it is now.
Sure the between-grade problem will always be there.

Today''s D-Z scale has 23 grades and the price difference between two grades can be huge so there is much at stake in borderline decisions.
If there were 100 color grades the price difference between 11 and 12 would be very small so there''s very little at stake.

 

[Dancing Fire]

Date: 3/9/2010 1:42:46 PM
Author: Tom Gelb
Just as an FYI at the GIA and I believe most other labs the master stones are placed at the highest end of a color range so if a diamond is better (has less color) than the F masterstone then it would be graded as an E, if it was better than the E masterstone then it would be a D.

I hope this helps.

thanks,Tom. good to know that infor.

 

[kristie]

I think in past PS threads, it was mostly stated that AGS was softer on color than GIA. However, my personal experience is not that......

I just had two AGS diamonds brought in to view with my appraiser. One was a 2.54 H and the other was a 2.45 G. BOTH stones were their respective graded colors against the master set.

There are bound to be little variances in both GIA and AGS once in a great while. GIA and AGS uses humans to grade diamonds; therefore, there is no "perfect" science to it......it is in the opinion of whoever doing the grading is....there are always going to be small mistakes/differences of opinion made, it is the nature of the beast. Rare, most likely......impossible, no.

 

[newguy2010]

Thanks everyone for chiming in. This process of looking for a ring is quite overwhelming.

 

[dimonbob]

You all need to know that both GIA and AGS labs use three humans to color grade diamonds. Also remember that the graders are all professionial diamond graders. That is all they do, day after day. If there is a question as to the color or clearity of a diamond, other graders jump in. Subjective yes, but when you have that many people grading a stone the margin for error is super small.

Also know that a small thing like the pills you may take for a cold or some other reason can play with your color vision. The people at the labs know this.

If you are in a jewelry store and showing them your new diamond you got from someone on the internet they can play all kinds of games to make you think the diamond is not what it is supposed to be. Their job is to get you to buy one of their diamonds and they do that by making the diamond you purchased somewhere else look bad.

Be careful!

dimonbob