Amethyst
Is an all-healer stone. It is used for anxiety, depression, and healing of addictions, creating calm and emotional release, balancing your emotions. It is a stone of change and transformation, out with the old in with the new. This will instill a spiritual awareness working with the crown Chakra to instill peace and serenity in your life. 
Physically it can boost mental stability, help the immune system, release tension & migraines and promote deeper sleep.