One of the most abundant minerals in the Earth's crust, quartz displays the greatest profusion of colors, patterns, and textures of any mineral. Gems cut from individual quartz crystals include amethyst, smoky quartz, rock crystal, citrine, and rose quartz. Finely grained quartz, which ranges from translucent to opaque, is typically carved or cut as cabochons or beads.
Sometimes mistaken for jade, aventurine is a compact variety of translucent to opaque quartz. Small inclusions of shiny minerals give this stone a sparkling effect, called aventurescence. Typically green, aventurine can also be peach, brown, or blue.