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Symmetry- How Does It Affect Visual Performance?


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Ummm. GIA 'excellent' requires at least VG on both polish and symmetry and AGS 'ideal' requires 'ideal' for both. Neither lab will give their top cut grade to a stone that has 'good' in either symmetry or polish. I point this out because you must be using some unusual definition of ideal in order to get these results. That's a big deal and it affects both the look fo the stone and the prices.

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Alternative point of view: if the only reason why a round stone is not making AGS "ideal" is because of symmetry and/or polish, and one or both are "excellent", I wouldn't worry overmuch. GIA "excellent" proportions with "good" polish and/or symmetry is more iffy.


The problem is that AGS only tells you if the reason for not making "ideal" is polish or symmetry in some documents, and GIA doesn't tell you at all what the reason for the downgrade is. You can pick up clues from using the FacetWare cut estimator, but again you don't have all the info on the report.


What worries me (and I guess Neil) is that your vendors seem to be using the word "ideal" rather loosely, and if that is the case, chances are that the diamonds you are considering are far from "ideal" in more ways than polish or symmetry.

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