Amethyst
Peace, clairvoyance, emotional protection, and sobriety. The purple variety of quartz is essentially the yogi of gemstones: it's about staying grounded while maintaining some higher spiritual perspective. Wearing it while meditating is said to deepen the practice and create a heightened awareness; clairvoyants and psychics rely on the stone to amplify intuition and open all spiritual channels. (Many recommend sleeping with amethyst under your pillow in order to thwart insomnia and encourage lucid dreaming). It's also a healing stone, and can provide relief and peace even in the face of addiction and emotional trauma.