DIAMOND ANATOMY
Once cut and polished, all diamonds possess a shared set of characteristics, often referred to as the anatomy of the diamond. While the individual proportions, angles and placement of these common characteristics vary for diamonds of different shapes, their definition is the same.
In the standard round brilliant, there are 57 facets. 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. 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 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. All of these facets work together creating each diamond’s unique appearance.
In the standard round brilliant, there are 57 facets. 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. 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 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. All of these facets work together creating each diamond’s unique appearance.
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TABLE
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. It is reported to the nearest whole percent (1%). Table size can have a significant impact on the diamond’s face-up appearance, especially when it’s paired with certain combinations of crown and pavilion angles. GIRDLE
Girdle thickness percentage is the average thickness of a diamond’s girdle, measured at the eight bezel/main “hill” positions, and expressed as a percentage of average girdle diameter. Hill positions are the “thick places” located where the bezel and main facets meet. It is reported to the nearest half of a percent (0.5%). Girdle thickness is visually assessed at the "valley" positions, as a range between the thinnest (minimum) and the thickest (maximum) areas. Valley positions are the "thin places" located between the bezel/main intersection and where the upper and lower halves meet. CULET
Culet size is described as the width of the culet facet, when present, relative to a round diamond’s average girdle diameter. Descriptions include none, very small, small, medium, slightly large, large, very large, and extremely large. "None" is used when there is no culet facet, which is sometimes referred to by the trade as a “pointed” culet. Larger culets can have a negative effect on the diamond’s face-up appearance, specifically affecting its pattern, and lowering its cut grade. |
CROWN
Crown angle is the measured angle between the bezel facet plane and the table plane. The average of eight crown angle measurements is reported to the nearest half of a degree (0.5°). Crown height percentage is the diamond’s crown height, measured from the table to the intersection of the bezel facet and the girdle, expressed as a percentage of its average girdle diameter. It is reported to the nearest half of a percent (0.5%). PAVILION
Pavilion angle is the measured angle between the pavilion main facet plane and the table plane. Pavilion depth percentage is the diamond’s pavilion depth, measured from the culet to the intersection of the pavilion main facet and the girdle, expressed as a percentage of its average girdle diameter. It is reported to the nearest half of a percent (0.5%). |