AGS DQD Grading Reports (old and new)

[JohnQuixote]

AGS DQD Grading Reports (old and new)

The AGS DQD, or Diamond Quality Document is highly regarded. It includes extensive information on proportions and provides a grading analysis of color, clarity, carat weight and cut. The DQD is the only report that awards the term ‘Ideal’ as its highest grade (the AGS DQR and commensurate GIA documents report ‘Excellent’ as the top grade). As of July 2005 there are 2 versions of the DQD for round brilliant diamonds. They differ in the way cut is judged.

* The OLD DQD judges cut based on proportions (external measurements)
* The NEW DQD judges cut by measuring light performance. This is more discriminating.

DQDs for shapes other than round also judge cut based on light-performance.

Note: If requested by the manufacturer, the AGS will still grade round diamonds using the old proportions-based DQD. Buyers should know that some diamonds cut to the outer limits of AGS0 under the old system will not receive AGS0 grade under the new performance-based system.

 

[JohnQuixote]

Examples

OLD DQD (proportions-based)

Under this system a diamond is graded entirely by external measurements, polish and symmetry. It is not analyzed for face-up light performance.

Note Ideal grades in:

Polish (evaluates the smooth, mirror-like finish)
Symmetry (evaluated how well facet junctions meet and uniformity of the diamond’s shape)
Proportions (evaluates external measurements, comparing them to proven ranges)

 

[JohnQuixote]

NEW DQD (performance-based)

Under this system each diamond is individually measured for face-up light performance as well as proportions and finish details.

Note 0 (Ideal) grades in:

Light Performance (evaluates angular spectrum via modeling and ray-tracing of each diamond)
Proportions (evaluates values associated with weight ratio, durability, tilt, girdle and culet)
Finish (evaluated both polish and symmetry, per above, combined into one grade)

 

[JohnQuixote]

DQR (Diamond Quality Report)

Another report offered by the AGS is the Diamond Quality Document, or DQR.

This document is less expensive to acquire. It reports major proportions information, but does not report a grade for cut. Additionally, the highest grade awarded in polish and symmetry is ‘Excellent:’ Even diamonds which qualify for ‘Ideal’ (on a DQD) will be reported as ‘Excellent’ on a DQR.

 

[JohnQuixote]

Notes:

1. Old DQD vs. New DQD

When considering an old DQD issued after 2005 it is prudent to inquire why the diamond was not requested for grading under the new system.

2. AGS0 and AGS000

If a seller advertises a diamond as AGS0 or AGS000 when not accompanied by an AGS report it should be questioned. The American Gem Society licenses its grading system to AGSL. The only people authorized to use the AGS grading system are:

• Members of the American Gem Society
• AGSL

A seller can represent a diamond as being an AGS Ideal 0 if they back it up with an AGSL report. They can also represent a diamond as being an AGS Ideal 0 cut if they are a member of the American Gem Society, with or without an AGSL report. If someone is not a member of the American Gem Society, they can’t legally or ethically represent a diamond as an AGS Ideal 0 cut without an AGSL report.

3. ‘Ideal’ diamonds

The term ‘Ideal’ has fallen into the trade lexicon as being commensurate with Excellent. Though not entirely correct, diamonds that are advertised with the word Ideal in cut (when not accompanied by an AGS document) should be expected to conform to either the old AGS Ideal proportions range (1996-2005), or new AGS proprietary grading.

The only way to be certain a diamond will receive the AGS0 or AGS Ideal 0 grade is to submit the diamond to AGS.

More information: http://www.agslab.com/faqs.htmlhttp://www.agslab.com/faqs_con_documentation.html

 

[He Scores]

RE: * The OLD DQD judges cut based on proportions (external measurements)
* The NEW DQD judges cut by measuring light performance. This is more discriminating.

John, while I may sound like I''m spewing sour grapes, I feel entirely different. IMHO, light performance is more subjective than external measurements. Light performance should not be labeled "cut grade". Light performance is made up of a variety of factors such as color saturation and flaws that are beyond a cutter''s control. Also, like I mentioned in the "pasting" thread, the strict face up viewing position that is used as a standard for evaluating performance is exclusive and doesn''t *ahem*

reflect all the ways a diamond''s performance is able to be observed.

Recently I had the oportunity to have an evaluator supply me with the measurement data from two Eightstar diamonds that he thought were the two "tightest" stones he has seen and while they both scored very high on my BrayScore cut analysis, there was a 2-3% difference between the two. Imagine what the range of differences would be for that brand of diamonds, or for any brand for that matter! In the world of financing and pricing diamonds, that means something. Based on this one time experience I have to politely disagree with you that measuring light performance is more discriminating. It may be it is more discriminating than AGS''s OLD cut grade, but that doesn''t mean that there isn''t a better way to interpret the physical measurments of a diamond.

Respectfully,
Bill Bray
Diamond Cutter

 

[JohnQuixote]

Date: 5/24/2006 8:53:41 AM
Author: He Scores

RE: * The OLD DQD judges cut based on proportions (external measurements)
* The NEW DQD judges cut by measuring light performance. This is more discriminating.

John, while I may sound like I''m spewing sour grapes, I feel entirely different. IMHO, light performance is more subjective than external measurements. Light performance should not be labeled ''cut grade''. Light performance is made up of a variety of factors such as color saturation and flaws that are beyond a cutter''s control. Also, like I mentioned in the ''pasting'' thread, the strict face up viewing position that is used as a standard for evaluating performance is exclusive and doesn''t *ahem*

reflect all the ways a diamond''s performance is able to be observed.

Recently I had the oportunity to have an evaluator supply me with the measurement data from two Eightstar diamonds that he thought were the two ''tightest'' stones he has seen and while they both scored very high on my BrayScore cut analysis, there was a 2-3% difference between the two. Imagine what the range of differences would be for that brand of diamonds, or for any brand for that matter! In the world of financing and pricing diamonds, that means something. Based on this one time experience I have to politely disagree with you that measuring light performance is more discriminating. It may be it is more discriminating than AGS''s OLD cut grade, but that doesn''t mean that there isn''t a better way to interpret the physical measurments of a diamond.

Respectfully,
Bill Bray
Diamond Cutter

Hi Bill,

This thread is about AGS documents only. New shoppers sometimes express confusion when they have a DQR and can''t find the cut grade, or have the old-style DQD and can''t locate light performance info. Diamonds cut to the old outer limits no longer qualify for ''Ideal'' using the new DQD, so the new report is more discriminating, certainly relative to this FAQ.

Further - in the macro, based on my experience with AGS angular spectrum/forward & reverse ray tracing I may not agree with you, but I would enjoy hearing more. If you start a thread in ''Rocky Talky'' to discuss your POV it would be *ahem* illuminating.

 

[He Scores]

John

If I get a chance to break away from the bench to figure out what I was saying, I'll start a new thread.

I'd like to sit down with you in Vegas just to discuss these types of things.


Bill