The quality of a diamond’s polish is a measure of how well it has been cut, and is determined by looking at the straightness of the facet edges, whether traces of lines or blemishes remain on the diamond, and the visibility of any blemish marks on the diamond. The rule of thumb is that the finer the polish, the finer the cut, and therefore the more brilliant the diamond.

In relation to the girdle, polish is optional at the discretion of the cutter and has no effect on value or beauty, since light is not reflected through the girdle. The GIA uses the following letter scale to denote a diamond’s polish:

E – Excellent

VG – Very Good

G – Good

F – Fair

P – Poor