Culet Bottom Facet on a Gemstone

Culet from "Culus" Meaning "Bottom"

Culet correctly pronounced "kyoo-lit" comes from the Latin "culus" meaning "bottom".

The culet is the facet at the bottom of a cut gemstone although not all faceted gemstones have one.

In some gemstones the culet is closed which means the tip comes to a sharp point.  Although a closed culet actually means there's no culet at all, many still refer to the pointed tip of a faceted gemstone as being the culet.