Small, finger-like wires that attach to a gemstone's bezel and are bent over the stone's edges to hold it in place. quartz Quartz is a commonly found crystalline mineral that comes in many forms. Types of quartz include amethyst, aventurine, citrine, opal, rock crystal, tiger's eye, rose quartz and many others. Quartz measures 7.0 on the Mohs hardness scale. radiant cut A rectangular gemstone that combines the shape of an emerald cut with the sparkle of a brilliant cut. A radiant cut has 70 facets.