Bezel facets

The bezel facets are the eight large kite-shaped facets on the crown of a round brilliant. They sit between the table (in the center) and the girdle (at the perimeter), tilted at the crown angle. On a GIA Excellent round the crown angle measured on the bezel facets sits at 33.5° to 35.5°.

Bezel facets carry most of a round brilliant's fire because they tilt incoming light at the steepest angle on the crown. White light entering through a bezel facet refracts at the crown angle, hits a pavilion main, totally internally reflects across to the opposite pavilion main, and returns through a different bezel facet on the way out. The refraction at each diamond-air boundary disperses the white light into its spectral components — the rainbow flashes the trade calls fire. Steeper bezel angles refract more steeply, producing more visible fire at the cost of brilliance.

The eight bezel facets define the crown's structural geometry. They share short edges with the eight star facets (the small triangular facets touching the table) and long edges with the upper-half facets (the sixteen small triangular facets touching the girdle). The arrangement is sometimes called the "stars and bezels" pattern; the visible eight-fold symmetry of a face-up round is the bezel facets reading through.

Bezel facet symmetry is what makes the hearts-and-arrows pattern possible. The eight arrows visible face-up under an H&A viewer are the eight pavilion mains reflected through the bezel facets. If the bezels are not perfectly symmetric, the arrowheads do not line up. AGS Ideal-0 stones routinely show H&A patterns because the AGS Performance Grading Standard penalises bezel asymmetry tightly; GIA Excellent admits more bezel variation, which is why not every GIA 3EX round shows H&A.

The interaction between bezel facets and table size determines the spread/fire ratio. A 54% table leaves more crown area for the bezels to occupy, producing more fire. A 60% table compresses the bezels into a narrower band at the perimeter and reduces both fire and overall crown contribution to light return — which is one reason large-table commercial rounds look bright but flat. AGS Light Performance grading reads bezel area directly via ray-trace; GIA approximates it via the published proportion bands.

For a buyer comparing rounds, the bezel facets are the facets to look at face-up: they are the eight large flashes you see when you tilt the stone in light.