Birthstones
The Particular birthstones associated with each month vary from one decade to the next. A modern European set of associations is shown here:

January - Garnet
February - Amethyst
March - Aquamarine
April - Diamond
May - Emerald
June - Pearl
July - Ruby
August - Peridot
September - Sapphire
October - Opal
November - Topaz
December - Turquoise

Gemstones have been associated with particular months of the year since ancient times. In astrology, each of the 12 signs of the zodiac is associated with one or two gemstones, which are thought to resonate with the essential character of the person born under that sign and consequently to bring the person luck.

A hugely contentious subject between scientists and New Age practitioners is that of "crystal healing." Crystal healers claim that certain crystals - particularly quartz - give off "healing energy" when placed on the body, a claim contested by mineralogists, who recognize the impossibility of this given the minutely bound and intricately balanced energies that create a crystal in the first place. Yet anecdotal evidence from many sources suggests that when patients are treated by crystal healers, healing does occur in many instances.

A new field of medical research suggests that the state of the immune system (and hence the state of health) is profoundly influenced by both conscious and unconscious mental and emotional factors. Perhaps it is the belief that the crystal will heal the body that causes it to heal, rather than the crystal itself..

Smithsonian "Rock and Gem" - A definitive guide to rocks, gems, minerals and fossils