Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, and has often been used for hardstone carvings, such as the Lothair Crystal. Common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others.
Serpentine is a gem-quality hydrated magnesium silicate, usually green, yellowish-green, or brownish-green in color. Its name is thought to be derived from its serpent-like green colors. Serpentine is not just a gemstone, but rather, it is a group of minerals which includes up to 20 different related members.