The design and craftsmanship of the diamond considers weight ratio (weight of the diamond relative to its diameter), the diamond's girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.

Cut is oftentimes confused with the shape of the diamond but cut refers to a stone’s facet arrangement. Shape refers to the outline of the stone. The most common diamond shape used in jewelry is round, as seen in the standard round brilliant cut. All other diamond shapes are known as fancy shapes. Traditional fancy shapes include the marquise, pear, oval and octagonal (as seen in the emerald cut). Square, cushion (square with rounded edges), triangle, and a variety of other shapes are also gaining popularity in diamond jewelry.

TABLE: The largest facet of a gemstone. 

CROWN: The top portion of a diamond extending from the girdle to the table. 

GIRDLE: The intersection of the crown and pavilion which defines the perimeter of the diamond. GIA also offers optional laser inscription with its reports (included with the GIA Diamond Dossier®) where the diamond’s report number is inscribed on the diamond’s girdle.

CULET: The facet at the tip of the gemstone.

PAVILION: The bottom portion of a diamond, extending from the girdle to the culet. A pavilion depth that’s too shallow or too deep will allow light to escape from the side of the stone, or leak out of the bottom. A well-cut diamond can let more light return through the crown.