All facets of these cuts may be divided into types, or layers: table, star facets, main crown facets (also known as bezel facets), upper girdle facets, lower girdle facets (also known as halves), and main pavilion facets.

A stone is positioned in the standard orientation, that is, with its table horizontal and facing downwards. Slope and azimuth angles are calculated and reported for each facet. The facets are grouped by types and ordered by azimuth within each type.

Azimuth is measured in the range from 0 to 360 degrees. Slope is measured in the range from 0 to 90 degrees. Table facet has zero slope by definition.

There are 56 slopes and as much azimuths in a round brilliant cut. Other cuts may vary in this regard.

Star Angle

This is the slope angle of the star facets.

Star Angle (symmetry)

Star Angle (symmetry) is defined as the maximum difference of Star Angle measurements, i.e. the same as deviation of Star Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.

Crown Angle

This is the slope angle of the main crown facets.

Crown Angle (symmetry)

Crown Angle (symmetry) is defined as the maximum difference of Crown Angle measurements, i.e. the same as deviation of Crown Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.

Upper Girdle Angle

This is the slope angle of the upper girdle facets.

Upper Girdle Angle (symmetry)

Upper Girdle Angle (symmetry) is defined as the maximum difference of Upper Girdle Angle measurements, i.e. the same as deviation of Upper Girdle Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.

Lower Girdle Angle

This is the slope angle of the lower girdle facets.

Lower Girdle Angle (symmetry)

Lower Girdle Angle (symmetry) is defined as the maximum difference of Lower Girdle Angle measurements, i.e. the same as deviation of Lower Girdle Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.

Pavilion Angle

This is the slope angle of the main pavilion facets.

Pavilion Angle (symmetry)

Pavilion Angle (symmetry) is defined as the maximum difference of Pavilion Angle measurements, i.e. the same as deviation of Pavilion Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.

Star Facets Azimuth

This is the azimuth angle of the star facets.

Crown Facets Azimuth

This is the azimuth angle of the main crown facets.

Upper Girdle Facets Azimuth

This is the azimuth angle of the upper girdle facets.

Lower Girdle Facets Azimuth

This is the azimuth angle of the lower girdle facets.

Pavilion Facets Azimuth

This is the azimuth angle of the main pavilion facets.