Birthstones for Signs of the Zodiac 

There are birthstones for the month in which you were born, but an alternative system assigns birthstones to your sign of the zodiac. Astrological birthstones predate monthly birthstones, coming from a time when it was considered wise to consult your astrologer rather than your jeweler before purchasing a gem. Note that some signs have ambiguous beginning/ending dates. People born on these dates are said to be 'on the cusps' or to have 'borderline dates'. If you are born on a cusp date, your sign depends on the time, date, and place of your birth.