Amethyst is an extremely sought-after gem which has been valued by many civilizations since antiquity. A variety of vitreous quartz, amethyst often forms dramatic prismatic crystals which are often formed into jewelry without being cut. Brazil and Uruguay are common sources of high quality amethyst. In the early Christian church, amethyst was believed to guard against intoxication, hence its derivation from the Greek "amethustos," meaning "not drunk."

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.