Birthstones have existed for many cultures with their own calendars throughout history, including mentions in the Bible about the Breastplate of Aaron and the foundation stones of the new Jerusalem. The birthstones most of us know were made official by Jewelers of America in 1912, and tanzanite for December was added by the American Gem Trade Association in 2002. Whatever their origin, birthstones are now widely known as a thoughtful, personal gift for men, women, and children.