06/05/2026
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, typically mounted to face the viewer. 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 and 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 influencing 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. However, 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.
Learn more about picking the best round brilliant diamond at the link in our bio.
