Quartz is one of the most common crystal minerals on Earth, and offers an amazing variety used in jewelry. Gemstone quartz is known by many names, including agate, amethyst, bloodstone, carnelian, citrine, jasper, rose quartz, and smoky quartz.
Quartz varieties are commonly separated into two groups based on the size of the individual grains or crystals; Macrocrystalline Quartz, in which individual crystals are visible to the unaided eye, and Cryptocrystalline Quartz, in which crystals are only visible under high magnification.
Ranging from light, pinkish violet to deepest black, Quartz can be found in almost every color. Quartz is rated at 6.5 to 7 on the Mohs Scale of Hardness.