Brightness – The amount of white light returned to the observer.

Brilliance – Brightness with positive contrast effects.

Contrast – The light and dark patterns seen when observing a faceted diamond. It can be positive or negative in its optical effect.

Culet – The point on the bottom of a diamond's pavilion. A diamond's culet may be pointed or it may be blunted with a small facet.

Dispersion – The separation of white light into spectral colors.

Durability – Resistance to chipping or breaking.

Girdle – The band around the outer circumference or edge of a diamond.

Leakage – Areas that do not return light.

Light Performance – An analysis of brightness, dispersion, leakage, and contrast.

Polish – The quality of the diamond's surface and edges.

Symmetry – The exactness of the balance and evenness of the diamond's shape and facets.

Tilt – The point at which the girdle reflects under the table facet.

Weight Ratio – The millimeter footprint of a diamond versus its weight.