Average Girdle Diameter:
The result achieved by adding the smallest and largest girdle diameter measurements of a round brilliant and dividing it by two.
The appearance, or extent, of internal and external reflections of “white” light seen in a polish diamond when it is viewed face-up.
The care that goes into the fashioning of a polish diamond, as confirmed by its finish.
The angle formed by the bezel facets and the girdle plane
The distance from the girdle plane to the table
Crown Height Percentage:
Crown height expressed as a percentage of average girdle diameter. Crown height % = (avg crown height ÷ avg diameter) x 100
The size of the facet at the bottom of the diamond where the pavilion mains meet. Its descriptions are none, very small, small, medium, slightly large, large, very large, and extremely large.
A diamond’s physical shape, including its finish, proportions, and durability. It’s determined by decisions made during the fashioning process.
The quality of the polish and the symmetry of the cut of a fashioned gemstone.
The width of a fashioned gem’s girdle, assessed at the thin areas, or “valleys”. Descriptions include extremely thin, very thin, thin, medium, slightly thick, thick, very thick, and extremely thick.
Girdle Thickness Percentage:
Girdle thickness expressed as a percentage of average girdle diameter, assessed at the thick areas, or “hills”.
Lower Girdle Facet Percentage:
The length of the lower girdle facets expressed as a percentage of the total distance between the girdle and the culet.
The quality of a faceted diamond’s proportions and finish.
The angle formed by the pavilion mains and the girdle plane
The distance from the girdle plane to the culet
Pavilion Depth Percentage:
Pavilion depth expressed as a percentage of average girdle diameter. Pavilion depth % = (avg pavilion depth ÷ avg diameter) x 100
The overall condition of a finished diamond’s facet surface
The angles and relative measurement of a polish diamond, and the relationships between them
Star Facet Length Percentage:
The length of the star facets expressed as a percentage of the total distance between the girdle and the edge of the table facet
The precision of a finished diamond’s shape and the placement of its facets
A round brilliant’s table size expressed as a percentage of its average girdle diameter. Table % = (avg table size ÷ avg diameter) x 100
A figure arrived at by measuring a round brilliant’s table in four directions and dividing by four
Total Depth Percentage:
Table-to-culet depth expressed as a percentage of average girdle diameter. Total depth % = (total depth ÷ avg diameter) x 100