As I strive to learn more about jewelry making, I have added gemology to my studies. With that I have discovered some interesting facts about birthstones. Each calendar month has a birthstone, or two, or more, assigned to it. The idea of gemstones assigned to each month is an ancient one. Traced back the Breastplate worn by Aaron in the Book of Exodus in the Bible, the breastplate had 12 gemstones representing the 12 tribes of Israel. In the 5th century, St. Jerome made the connection of the 12 tribes to the 12 zodiac signs and their corresponding gems. However, the idea of each month having a birthstone is a relatively modern idea, as the zodiac do not follow the months separately. The original modern list was first written down in 1912 by the National Association of Jewelers, and has remained unchanged. Each month Precious Metalz will publish information and interesting facts about the modern birthstones. You can also go to GIA.edu to read many interesting facts about gems, precious gems and stones.