The cut of a diamond determines its brilliance. There is no single measurement of a diamond that defines its cut, but rather a collection of measurements and observations that determine the relationship between a diamond’s light performance, dimensions and finish. Most gemologists consider cut the most important diamond characteristic because even if a diamond has perfect color and clarity, a diamond with a poor cut will have dulled brilliance.
How a Diamond is Cut
Determining a diamond’s cut grade, however, goes beyond simple measurements of width and depth. Using an optical measuring device, a three-dimensional model is created to determine the diamond’s proportions and angles. The interrelations between these various dimensions will greatly affect how light reacts once it enters and how it behaves once it exits; by using sophisticated computer modeling, it is possible to trace light behavior and measure its levels of brightness, fire and scintillation – the face-up appearance.
: The width of the diamond as measured through the girdle.
: The largest facet of a gemstone.
: The top portion of a diamond extending from the girdle to the table.
: The bottom portion of a diamond, extending from the girdle to the culet.
: The facet at the tip of a gemstone. The preferred culet is not visible with the unaided eye (graded “none” or “small”).
: The intersection of the crown and pavilion which defines the perimeter of the diamond.
: The height of a gemstone measured from the culet to the table.