Pavilion mains are the 8 long facets of a round brilliant's pavilion that run from the girdle to the culet.
In more detail
The pavilion angle is measured on the mains. In a hearts and arrows viewer, each arrow's shaft is a pavilion main, reflected in the main opposite it.
On a grading report
Their slope is the pavilion angle on the proportion diagram.
Related terms
- Pavilion angle: The pavilion angle is the slope of the pavilion mains, measured against the plane of the girdle.
- Lower half facet: Lower half facets are the 16 long, thin triangles along the pavilion edge of a round brilliant. There are two between each pair of pavilion mains.
- Hearts and arrows: Hearts and arrows is a pattern that a precisely cut round brilliant shows in a reflector viewer. Face-up it shows eight arrows, and face-down eight hearts.
- Pavilion: The pavilion is the cone-shaped part of a cut stone below the girdle. A standard round brilliant has 24 pavilion facets: 8 mains and 16 lower halves.