Cut grading only tends to be provided for Round diamonds. This is because it is extremely difficult to assess the ideal proportions of the likes of Marquise and Cushion. However, there are some experts that have done research about the ideal proportions for these shapes, and thus we will provide you with a small guide below.

In short: GIA assigns formal cut grades (Excellent → Poor) only to round brilliants — fancy shapes (oval, princess, emerald, cushion, marquise, pear, heart, radiant, Asscher) carry no official cut grade because optimal proportions vary by silhouette. Judge fancy cuts by length-to-width ratio, light-return symmetry, bow-tie severity in elongated cuts, and table-to-girdle alignment. Polish and symmetry grades still appear on every certificate.