Good cut: A diamond that might be slightly deeper or shallower, or have a slightly larger or smaller table facet, compared to an Ideal cut. Cutters may choose a Good cut in order to strike a balance between cut and carat weight retention. Diamonds with a Good cut grade reflect most of the light entering them and are an excellent. Represents roughly the top 25% of diamond quality based on cut. Reflects most light that enters. Much less expensive than a very good cut.
Cut Grading Systems analyze the light performance of a faceted diamond and measure the light rays traveling through all the facets in 3 dimensions instead of 2 dimensions.
And the cut grade rating determines the quantity and quality of light being returned to the viewer. In addition to proportion, symmetry and polish, brightness, dispersion, leakage, contrast and spread are also considered when assigning the final cut grade. Laboratories use the following attributes of a diamond to help determine the cut grade: depth %, table %, crown angle, pavilion angle, star length, girdle, polish, symmetry, and culet size. The Polygon Cut Grade feature applies to the standard round brilliant diamond cuts across all clarity ranges from the D-to-Z color-grading scale.