Before we go into the grading of a diamond, let us get familiar with some of the terms that we will be using, of which all of them are related to the anatomy of the diamond. Below we have a diagram depicting a round shape diamond and the names of the different basic parts.

Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.

Crown: The upper part of the diamond above the girdle. Consists of a large flat area on top called a table, and several facets below it

Girdle: The outer edge or the widest part of the diamond forming a band around the stone.

Pavilion: The bottom part of the Diamond, below the girdle.

Culet: A tiny flat facet that diamond cutters sometimes add at the bottom of a diamond’s pavilion. Its purpose is to protect the tip of the pavilion from being chipped or damaged. Once a diamond is set in jewelry, though, the setting itself generally provides the pavilion with sufficient protection from impact or wear. Large or extremely large culets were common in diamonds cut in the early part of this century, such as the Old European or Old Mine Cut. However, such large culets are rarely seen today. Most modern shapes have either no culet at all, or a small or very small culet.

Depth: The height of a diamond from the culet to the table. The depth is measured in millimeters.

Facet: The smooth, flat faces on the surface of a diamond. They allow light to both enter a diamond and reflect off its surface at different angles, creating the wonderful play of color and light for which diamonds are famous. The table below shows all the facets on a round brilliant cut diamond. A round brilliant has 58 facets (or 57 if there is no culet).