Culet

In gemology, a culet is a flat face on the bottom of a gemstone.

The culet is added largely to protect the integrity of the gemstone.

With other gemstones that are not subject to cleavage, the culet is added to protect the fragility of the pointed tip.

The culet has remained optional on many diamond cuts up to the present day, and was omitted from Marcel Tolkowsky's original designs for the round brilliant diamond cut in 1919.

Nonetheless, culet facets are common on modern brilliant-cut diamonds.