Cut

The Cut factor includes not only the shape and style but also the proportions, symmetry and finish (the make) of a diamond. A diamond with a "good make" will be bright, fiery, symmetrical, and sparkles with light. Shapes other than the standard round brilliant are called fancy cuts which include also heart, marquise, pear-shaped cut, emerald-cut, oval, and radiant.

Proportion refers to the angles and relative measurements of the diamond which eventually determine its optical properties. The three major parts of a polished diamond are the crown, the girdle, and the pavilion. Some polished diamonds have a very tiny flat facet at the bottom of the pavilion, called the culet. The large flat facet on the top of a polished diamond is called the table.

The distance from the bottom of the girdle to the culet is the pavilion depth. A pavilion depth that’s too shallow or too deep will allow light to escape and a well-cut diamond will direct more light through the crown.

Cutting a diamond to produce the maximum return of light depends on the interrelationship between three critical proportions – table size, crown angle and pavilion depth. These can be combined in many ways to yield equally bright round brilliant cut diamonds.

Symmetry refers to 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. The diamond’s polish refers to the condition of its girdle, and the precision of the cut.