diamond cuts
- Thread starter rmoreno
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I am pretty amazed anyone can see that (including the graders) !
You may want to inspect Garry's posts for a couple of colorful accounts of just how insignificant these grades are.
GIA's cut study includes a table summarizing their findings on how much visual impact grades have. That one is cited in the Diamond Journal (LINK). It seems weird that the makers of the grading system judge it so harshly: the survey basically says that even "fair" symmetry only has a "slight" visual effect and "excellent to very good" none at all.
AGS pretends their grades are even more hair splitting - so even more insignificant.
Not much more remains to add, as far as I understand
Neither is "optical symmetry" though - so neither "ideal" not "excellent" is responsible for the H&A pattern... if that is your concern. (link to one GIA Ex-Ex nowhere H&A... there were some AGS0 like this one I can retrace if relevant).
Hope the 0.2 helps
You may want to inspect Garry's posts for a couple of colorful accounts of just how insignificant these grades are.
GIA's cut study includes a table summarizing their findings on how much visual impact grades have. That one is cited in the Diamond Journal (LINK). It seems weird that the makers of the grading system judge it so harshly: the survey basically says that even "fair" symmetry only has a "slight" visual effect and "excellent to very good" none at all.
AGS pretends their grades are even more hair splitting - so even more insignificant.
Not much more remains to add, as far as I understand
Neither is "optical symmetry" though - so neither "ideal" not "excellent" is responsible for the H&A pattern... if that is your concern. (link to one GIA Ex-Ex nowhere H&A... there were some AGS0 like this one I can retrace if relevant).
Hope the 0.2 helps
JohnQuixote
Ideal_Rock
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- Sep 9, 2004
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- 5,212
Ruben,
The short answer is no
...Now for the long answer (forgive redundancy if I repeat things Ana has offered):
Nomenclature
The term “Ideal” is only used on the AGS Diamond Quality Document (DQD). The DQD is the top shelf AGS report - but not every stone that could receive Ideal grades is necessarily sent in for a DQD… Some are sent in for a Diamond Quality Report (DQR), which much resembles GIA’s lab report (Ex is the top rating given).
Here is a recent thread with examples of both a DQD and a DQR.
This is important to understand…Ideal polish and symmetry are reported as excellent on the DQR.
Visible Difference
To the meat of the question, and Ana’s main point: When splitting the Ideal or Ex hair, consider that the GIA concluded that there is no visible difference in diamonds with G, VG and Ex lab-graded symmetry and polish grades. This makes the difference in Ideal and Ex on a DQD or DQR even less significant, except to nomenclature fans who prize the term “Ideal” (of which there are, admittedly, plenty).
As for what is perceivable with your eyes, it’s good to be aware that what the labs grade, symmetry-wise is not optical symmetry. Here are some good reads on this:
Garry on symmetry grading
John on symmetry differences
The short answer is no
...Now for the long answer (forgive redundancy if I repeat things Ana has offered):
Nomenclature
The term “Ideal” is only used on the AGS Diamond Quality Document (DQD). The DQD is the top shelf AGS report - but not every stone that could receive Ideal grades is necessarily sent in for a DQD… Some are sent in for a Diamond Quality Report (DQR), which much resembles GIA’s lab report (Ex is the top rating given).
Here is a recent thread with examples of both a DQD and a DQR.
This is important to understand…Ideal polish and symmetry are reported as excellent on the DQR.
Visible Difference
To the meat of the question, and Ana’s main point: When splitting the Ideal or Ex hair, consider that the GIA concluded that there is no visible difference in diamonds with G, VG and Ex lab-graded symmetry and polish grades. This makes the difference in Ideal and Ex on a DQD or DQR even less significant, except to nomenclature fans who prize the term “Ideal” (of which there are, admittedly, plenty).
As for what is perceivable with your eyes, it’s good to be aware that what the labs grade, symmetry-wise is not optical symmetry. Here are some good reads on this:
Garry on symmetry grading
John on symmetry differences
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