Chalcedony is the general name for a variety of colored quartzes, many of which have a creamy appearance and luster. The gemstones given the name chalcedony are usually white to bright blue, while other colors have been given separate names--for instance, black onyx, green chrysoprase, and orange carnelian.

Tourmaline is a coveted stone that comes in a wide range of colors from black to pink, green and blue. Crystals which display more than one color together are common. A cross-section of a watermelon tourmaline crystal reveals green on the outside and pink within.