faceting

A process of cutting regular planes on stone in a predetermined pattern that is related to the stone’s crystalline structure.The first precious stones used for decorating jewelry were not faceted at all, but smoothed and rounded into the cabochon style (a cabochon is a stone with a flat back and a domed face). It was discovered, however, that some stones reflect more light if they are cut into facets, and so the face was cut into regular panes as in the rose cut. The backs of these early cut stones were still flat, but through experiment lapidaries learned to shape the bottom of a stone into a point (known as a pavilion) that further increased the gem’s “fire.”