Crown: This is the entire upper part of the diamond above the girdle.  It consists of the table surrounded by the main upper facet, star facet and upper girdle facet.  This is where you will see most of the brilliance in a diamond.

Girdle: This is the outer edge of the diamond.  It is the band that separates the crown from the pavilion.  The girdle can have one of three different types of finishes depending on the cutter... bruted, faceted or polished. 

Pavilion: This is the bottom part of the diamond below the girdle.  It consists of the lower main facets, lower girdle facets and the culet.  The height of the pavilion contributes to the brilliance of the diamond.  If the pavilion is too shallow or too deep, light entering the diamond will be lost through the bottom.

Facets are the smooth flat surface of the diamond.  It allows light to enter, reflect and exit the diamond creating the beautiful colors seen in diamonds.

Table: This is the flat facet on the top of the diamond.  It is the largest facet on the cut of any diamond and is usually oriented on top facing the viewer.  This is your main window into the beauty that makes a diamond.

Star Facet: Sharing a side with the table, these 8 facets are called Star facets.  This is because when the diamond is seen from the top, these eight facets appear like a star

Bezel Facet: This facet, also known as a kite facet because they look like a kite, extend from the table to the girdle.

Upper Girdle Facet: These facets join the kite facet with the girdle. There are two highlighted in the illustration.  They are simply mirror images of each other.

Lower Girdle Facet: These facets join the pavilion facet to the girdle.  There are two highlighted in the illustration.  They are simply mirror images of each other.

Pavilion Facet: This elongated kite shaped facet on the underside of the diamond connects to the girdle at a point to the culet.

Culet: This is the point at the bottom of the diamond.  It is sometimes polished as a flat facet to protect the diamond from  chipping while the other facets are polished or when the diamond is being mounted in jewelry.  More often, the culet is 'closed' to a point eliminating its visibility.  If the culet is cut too large, it acts like a window through the diamond and can be mistaken for an inclusion.

All diamonds, no matter if it is an uncut diamond or a finished diamond ready for sale, has to be measured.  This section will teach you how diamonds are measured and what all the numbers mean.

Girdle Diameter: Also called the Diamond Width, this is the diameter of the girdle in a round diamond.  Since not all round diamonds are perfectly round, a Diamond Grading report will display a range.  This is done by taking the measurements from at least 4 different points and listing the smallest and the largest numbers in the report.  For example, a report may say 6.24mm-6.26mmx3.70mm.  The diameter ranges from 6.23mm at its smallest and 6.26mm at its widest.  3.70mm is the total depth of the diamond.

Table Width: This is the size of the table taken at its widest point.  Non-round shapes such as pears use the smallest diameter (width as opposed to length).

Crown Height Percentage: This is calculated by dividing the crown height with girdle diameter.  The crown height of the diamond is measured from the table to the girdle.  For example, if the crown height is 1.01mm and the girdle diameter is 6.25mm, the calculation would be 1.01/6,25=0.162 = 16.2%, perfect for an ideal cut.

Pavilion Depth Percentage: This is calculated by dividing the pavilion height with the girdle diameter.  The pavilion height of the diamond is measured from the girdle to the culet.  For example, if the pavilion height is 2.69mm and the girdle diameter is 6.25mm, the calculation would be 2.69/6.25=0.43 = 43%, perfect for an ideal cut.

Girdle Thickness: This is the thickness of the girdle.  Girdles are not graded, but rather it is described by its appearance at its thinnest and thickest points.  The descriptions are, extremely thin, thin, medium, slightly thick, thick and extremely thick.  The shape of the diamond will determine which thickness is ideal.   For example, a round brilliant diamond would look best with a thin to slightly thick girdle.  A fancy cut diamond however would do best with a thin to thick girdle to protect it.

Depth: This is the overall depth of the diamond from the table to the pavilion. 

Crown angle: This is the angle that the crown facets intersects the girdle.  This slope is what helps to create the fire in a diamond.  White light entering at the different angles is refracted into its different wave lengths creating the beautiful colors seen in a diamond.

Table percentage: This is the percentage of the table diameter as compared to the entire diamond.  For example, an ideal table percentage for a round brilliant would be 55%.  This means that the table size is 55% the width of the girdle diameter.  For non-round diamonds, this measurement is done by dividing the table length at the wide point with the widest point of the girdle.

Symmetry: This refers to the exactness of the shape and arrangement of facets.  This can include small variations in the alignment of facets or centering of the culet to the diamond as shown in the illustration.  Symmetry is regarded as an indicator of the quality of a diamond's cut and is graded as Poor, Fair, Good, Very Good, Excellent and Ideal.