gemstone | Definition, History, Types, & Facts | Britannica
The four most common faceted forms are the brilliant cut, the step cut, the drop cut, and the rose cut. In addition to unfaceted stones being cabochon cut, some are engraved. High-speed, diamond-tipped cutting tools are used. The stone is hand-held against the tool, with the shape, symmetry, size, and depth of cut being determined by eye.