A tradition that many historians believe dates back to the Bible, birthstones are precious and semi-precious gems that are assigned to a particular month of the year. The month in which you were born dictates your birthstone: if your birthday is in January, the garnet is your birthstone, while April babies are blessed with diamonds. Birthstones are believed to bring good fortune to the wearer, together with the special properties that have been attributed to gemstones over the centuries. Rubies, for example - the birthstone of July - were worn in ancient times to ward off evil, while December's birthstone, turquoise, is often associated with success.