Amethyst

Amethyst is a violet or purple variety of quartz. The name comes from the Greek a ("not") and methuskein ("to intoxicate"), a reference to the belief that the stone protected its owner from drunkenness; the ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief that it would prevent intoxication.
Healing properties: Stone of spirituality and contentment. Amethyst can give the owner, inner peace and tranquility. It bestows stability, strength, and invigoration. It has been used to encourage and support sobriety. It is an excellent stone for one who is attempting to find freedom from addictive personalities (oneself or another). Calming, strong, protective qualities, healing and inspiration. Enhances one's psychic abilities.