Ancient astrologers turned to the heavens for answers as to why certain gem stones actually held magical powers.

They thought that the influence of your astrology sign over your fortune in life is strengthened by wearing, holding or carrying the stone associated with the constellation under which you were born.

This idea is based on the agreement that exists between all things. Your astral stone is more than a symbol of your astrology sign - it really receives the vibrations of the constellation and can strengthen the planetary or zodiacal influence.
There is no essential authority as to which gemstones are connected to each sign of the zodiac. Usually, I have listed first the traditional Hindu source for the astral stone of each sign, with other beliefs and traditions following it.

There are several stones scheduled for each sign, and in choosing your astral stones, you are advised to use the ones with which you feel a close connection.