The attraction of fancy shapes is largely the appeal of the shape itself. Round brilliant-cut diamonds are without a doubt more brilliant. Generally speaking, larger fancy shapes cost a little less than round diamonds. This reflects the larger yield cutters get by cutting a fancy shape that ‘fits’ into an unusually shaped piece of rough.
There are no ‘ideal’ fancies, but here are some tips. Expect to see a ‘bow-tie effect (usually dark but can be lighter) in the centre of longer/narrower diamonds like marquise, pear and oval diamonds.
The best tool for selecting fancy shaped diamonds is the ideal-scope .
Popular length to width ratios are marquise 2:1, heart 1:1, princess 1:1 or square and emerald cut 1.5:1.