|The Cut Scale primarily developed by GIA ranges from Excellent to Poor.It provides a cut quality grade for standard round brilliant diamonds that fall in the D-to-Z color range.
A polished diamond's beauty lies in its complex relationship with light: how light strikes the surface, how much enters the diamond, and how, and in what form light returns to your eye.
The result is a magnificent display of three attributes. Brightness is the combination of all white light reflecting from the surface and interior of a diamond. Fire describes the "flares" of color emitted from a diamond. Scintillation describes the flashes of light you see when the diamond, the light, or the observer moves.
A polished diamond's proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with fine proportions, symmetry, and polish optimize their interaction with light, and have increased brightness, fire, and scintillation.