![]() ![]() Table % = (average table size ÷ average girdle diameter) x 100 The table percentage is a calculated value obtained by the following formula: It is reported to the nearest whole percent (1%). The table percentage of a round brilliant diamond is the average of four table measurements (from bezel point to bezel point) expressed as a percentage of the average girdle diameter. Total depth % = (depth ÷ average girdle diameter) x 100 Table Percentage The total depth percentage is a calculated value obtained by the following formula: The total depth percentage of a round brilliant diamond is the table-to-culet depth, expressed as a percentage of the average girdle diameter and reported to the nearest tenth of a percent (0.1%). This proportion is used in calculating certain percentages such as table size, total depth, crown height, and pavilion depth. The average girdle diameter is a calculated value obtained by the following formula, which is then reported to the nearest hundredth of a millimeter (0.01 mm):Īverage girdle diameter = (minimum diameter + maximum diameter) ÷ 2 The diameter of a round diamond is the distance from one girdle edge to the opposite girdle edge, straight through the center.īecause even well-cut round diamonds are never perfectly round, the diameter is measured in several places, recording the minimum (smallest) and maximum (largest) measurements. All of these facets work together creating each diamond’s unique appearance. The pavilion facets, consisting of 16 lower halves, 8 mains, and an optional culet, reflect the light back through the crown to the viewer’s eye. The crown facets, consisting of 8 bezels, 8 stars, and 16 upper halves, gather and disperse light to create brightness, fire, and a scintillating pattern of light and dark. The table facet, usually the largest facet on the diamond, helps gather light from above and either reflects it back to the observer or directs it into the diamond’s interior. In the standard round brilliant, there are 57 or 58 facets. Each part of a diamond makes its own contribution to the diamond’s appearance. This graphic illustrates the measured and visually assessed proportions that affect a round brilliant diamond’s cut grade.Ī specific set of terms is used to describe parts of a polished diamond. ![]()
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