symmetry & polish for fancies

[Bill D.]

I was looking at bluenile''s page and noticed that most GIA reports for fancies are between g/g and vg/vg for fancies. For rounds they are ex/ex. This is kind of puzzling.

How is the symmetry grade for fancy shaped diamonds like the princess and the flanders determined (what would make a princess have excellent symmetry)? How is the polish rating related to shape?

 

[dimonbob]

Hi Bill D.

The cutters will not make EX EX fancies until the market demands it. You are lucky to find a VG VG fancy.
A few years back, it was difficult to find a good selection of round EX EX. Now they are more plentiful.

 

[Bill D.]

Thanks for the information. So I assume that cutters tend produce g/g cuts to preserve weight and maximize profit and if the rough is such that better symmetry/polish can be achieved so be it.

From a practical perspective, can someone quantify what determines excellent symmetry, which deviations downgrade it and what is their relative magnitude? I could only find similar information for rounds.

 

[Giangi]

Be advised that you CAN tell the differences between a 'good' symmetry emerald or heart and a 'very good' or 'excellent'...

An Excellent rating implies negligible to minor symmetry characteristics as well as negligible polish marks. It's quite difficult to find an Ex/Ex...