This buying guide outlines the quality factors for crystalline varieties of quartz. Cryptocrystalline varieties, such as chalcedony and jasper, aren’t included.

Crystalline Quartz Buying and the Four Cs

The IGS quartz value listing has price guidelines for smoky quartz, rose quartz, rutilated and tourmalinated quartz, quartz with lepidocrocite, star quartz, and gold in quartz. Separate value listings for amethyst and citrine contain price guidelines for these varieties.

Color

Quartz is a large family of gemstones. Not surprisingly, it occurs in many colors and varieties.

Colorless

Without trace impurities, quartz is colorless. This abundant material occurs in very large sizes. Often called “rock crystal,” colorless quartz can serve as an inexpensive alternative to other colorless gemstones.

Doubly terminated rough crystals are somewhat rare. Gem enthusiasts sometimes erroneously call these gems “Herkimer diamonds.” This misnomer comes from their source, Herkimer, NY, where they occur in abundance. With high transparency, these gems sparkle when rough.

Smoky Quartz

Ranging in color from light tan to nearly black, smoky quartz can simulate imperial topaz. When faceted and set, these gems can make lovely jewelry pieces with their deep chocolate to opaque black tones. Although inexpensive and abundant, even in large sizes,…