Maximum variance on Measurements for Rounds

[Brookie]

What is the maximum variance you should consider on a round stone in the AAxBBxCC measurments for a round? By variance I mean the diffence between AA and BB numbers. Is there an industry standard of the maximum variance before it''s no longer considered round? Or is there any negative look or performance effects is the number is to large?

 

[strmrdr]

I look for .05 or better for a super-ideal cut
and .10 and under for ideal cut

 

[strmrdr]

I like tight diamonds where all the facets are closely matched in size and angle once you get too much variation in diameter that is no longer possible.