Gem quality druzy is created when a layer of tiny quartz crystals forms over the top of another stone. Natural druzy crystals can be colored themselves or take their color from the underlying stone. The surface of a druzy is sometimes coated with gold or other substances for a dramatic effect. Titanium druzy has been treated with a thin layer of titanium to give it a beautiful color and iridescent sheen.

Citrine is quartz generally occurring in a golden color. Citrine occurs naturally in Scotland and in the Ural Mountains of Russia. Much citrine available today is actually smoky quartz or amethyst that has been heat-treated to achieve its characteristic color.

Derived from "tapaz," the Sanskrit word for fire, topaz is one of the most brilliant cut gemstones in existence. Topaz comes in a variety of colors from yellow to blue, and deeper blues and pinks are often created by heat-treating stones. Brazil is the world's top exporter of topaz.