Smoky Quartz features prominently in my newest designs in the form of some spectacular and unsual concave faceted briolettes. This lovely brownish-black variety of quartz occurs naturally, but is also commonly created by irradiating or heat treating clear quartz. Hue ranges from blackish "smoky" to golden brown (sometimes named as a variety of citrine). It is a popular gem for unusual faceted cuts and is the national gem of Scotland. It pairs beautifully with citrine and deep smoky red Orissa garnet, which pick up the golden hues. Quartz itself is an enormous family of minerals composed of silicon dioxide. There are two varieties: macrocrystalline (crystals visible with the naked eye) and micro (or crypto) crystalline (crystals which cannot be seen without magnification.) The macrocrystalline quartzes include citrine, amethyst, aventurine, tigereye, and rose, smoky, rutilated, snowy and crystal (also called rock crystal) quartz. The cryptocrystalline quartzes are termed chalcedony and/or agate. (Also commonly marketed as "quartz" is a series of manmade forms of glass - these include cherry, blueberry, pineapple, and blue "quartz", as well as opalite.) Hardness: 7 Care: Generally very hardy and trouble free - colored varieties may alter in hue and intensity with exposure to intense heat or light.