Birthstones by Month and Zodiac

The tradition of allocating minerals to specific points of the solar cycle did not originate in modern retail catalogs. Its roots trace back to the Book of Exodus (chapter 28), which describes the Hoshen, or ceremonial Breastplate of Aaron. Mounted in four tiers of gold filigree were twelve precious stones, each inscribed with the name of one of the twelve tribes of Israel: sardius, topaz, carbuncle, emerald, sapphire, diamond, ligure, agate, amethyst, beryl, onyx, and jasper.

By the first century CE, Jewish-Roman historian Flavius Josephus and Saint Jerome connected these twelve breastplate stones directly to the twelve signs of the Zodiac and the twelve calendar months. In early Christian and Mediterranean traditions, it was customary to own all twelve gems and wear each individually during its corresponding month, believing the stone possessed peak energetic affinity while the sun traversed that quadrant.

The modern custom of wearing a single stone matched exclusively to one's birth date emerged in eighteenth-century Poland, bolstered by gem merchants arriving from Nuremberg and Central Europe. In August 1912, the American National Association of Jewelers (now Jewelers of America) convened in Kansas City to standardize the list, harmonizing confusing regional folklore and introducing commercially accessible transparent varieties like tanzanite and spinel in subsequent mid-century revisions.