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.
In more detail
Their reach toward the culet is the lower half length, and longer lower halves leave narrower mains. In the decades after 1919, cutters made them longer. That change later shaped the hearts in hearts and arrows stones.
On a grading report
Described on the proportion diagram by the lower half length.
Related terms
- Lower half length: Lower half length is how far the lower half facets reach from the girdle toward the culet. It is a percentage of that distance.
- Pavilion main: Pavilion mains are the 8 long facets of a round brilliant's pavilion that run from the girdle to the culet.
- 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.