What is a diamond cut grade?

A diamonds cut is often confused with its shape (round, heart, oval, marquise etc), but the cut grade refers to the balance of proportions achieved by the cutter and how well the facets interact with the light. A cut grade is only given to a round brilliant diamond as it is the most popular diamond shape and therefore the GIA has developed a specific system to assess the cut quality of round brilliant diamonds.

The cut grade considers the proportions of the facets that influence the diamond’s face-up appearance. These proportions allow GIA to evaluate how successfully a diamond interacts with light to create desirable visual effects such as:

Brightness: Internal and external white light reflected from a diamond.
Fire: The scattering of white light into all the colours of the rainbow.
Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond.

GIA’s diamond cut grade also considers the design and overall craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.

Why is a diamonds cut grade important?

The GIA cut scale for round brilliant diamonds in the D-to-Z diamond colour range contains 5 grades ranging from Excellent to Poor. Diamonds that achieve a higher cut grade are more desirable and have a higher value.

We recommend diamonds with a “very good” cut grade and above for maximum sparkle and light dispersion.

See the below cut grade comparison tool provided by the GIA.