Smoky quartz is a grey, translucent variety of quartz. It ranges in clarity from almost complete transparency to a brownish-gray crystal that is almost opaque. Some can also be black. Like other quartz gems, it is a silicon dioxide crystal. The smoky colour results from free silicon, formed from the silicon dioxide by natural irradiation.
Smoky Quartz is an important brown gemstone, and is used in various form of jewelry. It is especially used as ring and pendant centerpieces. Lesser quality stones, often with lighter color, are cut as cabochons or tumbled into beads. Large spheres and carvings are also cut from Smoky Quartz.
Few gemstones are confused with Smoky Quartz, though brown topaz can be the same color but is harder, and brown Diamonds have more fire and are much harder. Smoky Quartz may also resemble other black gemstones such as Schorl TourMalone and Melanite Garnet, but these gemstones are always opaque, whereas Smoky Quartz is usually at least translucent.
- Smoky Quartz and Rose Quartz are the varieties of Quartz least like Inferno Quartz.