Diamond Grading Cut

Cut (Fourth in the 4 C's)

Gemological Institute of America (GIA) Standards

Cut is perhaps the most overlooked of the Four C's of Diamond quality, yet it is very important since it affects not only a Diamond's beauty but value as well. A better cut gives a Diamond more brilliance, which to the consumer is what a Diamond is really all about.

The consumer often confuse a Diamond's "shape" with its "cut", most likely due to the industry's synonymous use of the term cut to describe a Diamonds shape (Diamond cut, Marquise cut, Round Brilliant cut ...) In reality, when we refer to the cut of a Diamond, we are really referring to a compilation of factors including brightness, fire, scintillation, design and craftsmanship, as well as proportion, dispersion, finish and symmetry.

Proportion: Proportion refers to the angles and relative measurements of a polished diamond. More than any other feature, proportions determine a diamond's optical properties. Studies have shown that table size, crown angle, and pavilion depth have a dramatic effect on a diamond's appearance. Proportions vary depending on the shape a diamond is cut into. Above is a chart to show the ideal cut for a round brilliant diamond.

Symmetry: A grading term for the exactness of shape and placement of facets. Variations in symmetry include off-center culets and tables, poor facet alignment, misshapen facets, out-of-round girdles, and wavy girdles.

Finish: Refers to the quality of a diamond’s polish, the condition of its girdle, and the precision of the cut. A well cut diamond, with well balanced proportions and high polish, can make light behave in breathtaking ways. The result is a magnificent display of brilliance, dispersion, and scintillation.

Brilliance: The combination of all the light reflections from the surface and the inside surface of the stone gives a polished diamond its brightness.

Dispersion: Sometimes called "fire", dispersion is the breaking up of white light into spectral hues and the "rainbow" colors you see when light passes through a prism. Diamonds are more dispersive than most other gems.

Scintillation: Sometimes called "sparkle", scintillation refers to the tiny flashes of light when the diamond, the light source, or the observer moves. It depends on the number, size, and position of the facets. The quality of the polish affects scintillation, as well.

Diamond (Cut)