A birthstone is a gift of a precious material (jewelry, mainly gemstones; themselves traditionally associated with various qualities) that symbolizes the month of birth in the Gregorian Calendar. Often combined with modern birthstone lists, traditional birthstones are older society-based birthstones. Since many different cultures had their own list, jewelers' lists are often inconsistent over what constitutes a traditional birthstone.

Early civilizations such as India and Babylon have attributed gemstones with magical properties. Over time, astrologers assigned gems of certain colors to the twelve signs of the zodiac to help people influence the planets in their favor.

Most gem scholars agree that the tradition of birthstones arose from the Breastplate of Aaron (read more below): a ceremonial religious garment set with twelve gemstones that represented the twelve tribes of Israel and also corresponded with the twelve signs of the zodiac and the twelve months of the year.