07/03/2025
Looking to pick an exceptional Round Brilliant Cut diamond? Save these tips on diamond anatomy!
- 𝐓𝐚𝐛𝐥𝐞: This is the largest facet at the top of a diamond. It allows light to shine into the diamond and reflect back out. A large table facet can make a diamond appear larger, but too large of a table facet can reduce the crown facets’ ability to disperse light. The ideal table size is between 52-62% of a diamond’s diameter.
- 𝐂𝐫𝐨𝐰𝐧: The crown facets at the top of the diamond consist of 8 bezels, 8 stars, and 16 upper halves. They gather and disperse light to create brightness, fire, and a scintillating pattern of light and dark. The crown angle – the angle between the bezel facet plane an the table plane – should be between 31.5 to 36.5 degrees.
- 𝐆𝐢𝐫𝐝𝐥𝐞: The girdle surrounds the middle portion of a diamond like a “belt,” Separating the crown from the pavilion. It should not be too thick, which can hide weight, or too thin, which may make the diamond vulnerable to chipping.
- 𝐏𝐚𝐯𝐢𝐥𝐢𝐨𝐧: The pavilion or bottom facets consist of 16 lower halves and 8 mains. They reflect light back through the crown into the viewer’s eye. The pavilion, angle, the average angle made by the diamond’s pavilion facets and girdle plane, is a key dimension relating to the stone’s brightness, and ideally falls between 40.6 – 41.8 degrees.
- 𝐂𝐮𝐥𝐞𝐭: The culet is an optional facet at the very bottom of the diamond. It can reduce the chance of the bottom tip chipping. An overly large culet can look like a distracting dark circle through the table facet.
Importantly, GIA considers how a diamond’s proportions relate to each other, rather than considering individual proportions in isolation.
