Amethyst is purple quartz, and is a meditative and calming stone. It works in the emotional, spiritual, and physical planes to provide calm, balance, patience, and peace. Amethyst is also beneficial when dealing with legal problems and money issues, which can lead to prosperity and abundance.
Emotionally, amethyst can help heal personal losses and grief. Amethyst has a gently sedative energy that promotes peacefulness, happiness, and contentment. It also brings emotional stability and inner strength, and can enhance flexibility and cooperation. Amethyst can help get rid of addictions (alcohol, drugs, smoking, etc.) and compulsive behaviors of all kinds.
In the psychic and spiritual realms, amethyst is an excellent all-purpose stone that can increase spirituality and enhance intuition and psychic powers of all kinds. It does this by making a clear connection between the earth plane and other planes and worlds. Amethyst is also excellent for meditation and lucid dreaming. It is known to open one’s channels to telepathy, past life regression, clairaudience, clairvoyance, and communication with angels. Amethyst also protects against psychic attacks, especially during spiritual work, and protects one from thieves, and protects travelers.
Physically amethyst is said by spiritual healers and mystical lore to heal the withdrawal symptoms of any sort of addiction, help with headaches, insomnia, arthritis, diabetes, pain relief, circulatory system issues, endocrine system problems, chronic fatigue, fibromyalgia, immune system deficiencies,asthma, phobias, pregnancy and preventing miscarriage, menopause, PMS, and general healing.
It is also said that Amethyst will protect from psychic vampires and should be left around windows and doors of a house to protect against their psychic attacks.
Amethyst is associated with the third eye and crown chakras primarily, but can also open the heart chakra.
(info from http://www.crystalsandjewelry.com/metaphysical_healing/stoneinfo/amethyst.html)