There are a large number of web sites and books on the subject. Some of these are listed below:
Crystals & Gemstones
How to Use Crystals
Crystal and Gemstone Therapy
What does the Bible say about crystals?
The Healing Gemstones
What does it Mean When You Are Attracted to a Particular Gemstone?
Top 10 Healing Gemstones
The Healing Power of Gemstones: In Tantra, Ayurveda, and Astrology [Paperback] by Harish Johari
Healing Crystals and Gemstones: From Amethyst to Zircon by Flora Peschek-B√∂hmer
Gemstone Energy Medicine: Healing Body, Mind And Spirit by Michael Katz
Healing with Crystals and Gemstones: Balance Your Chakras and Your Life by Daya Sarai Chocron
Healing Jewelry: Using Gemstones for Health & Well-Being by Mickey Baskett
The Women's Book of Healing: Auras, Chakras, Laying On of Hands, Crystals, Gemstones, and Colors [Paperback] by Diane Stein