The Modern American Birthstone List is the canonical monthly assignment of gemstones to calendar months adopted in 1912 at the convention of the National Association of Goldsmiths in Kansas City, Kansas. The list, intended to standardise a tradition that had previously been a patchwork of regional and cultural assignments, has remained the dominant North American reference for over a century, with formal additions made by the American Gem Trade Association and the Jewelers of America in 2002 and 2016. For the trade, the list is a perennial driver of retail traffic, gift-giving merchandising, and custom-jewellery commissions.

The 1912 list and its principal months

The agreed assignments were: garnet for January; amethyst for February; aquamarine for March; diamond for April; emerald for May; pearl for June; ruby for July; peridot for August; sapphire for September; opal for October; topaz for November; and turquoise for December. Several months received tourmaline, citrine, and zircon as alternates either at the time or shortly after; alternate stones for some months reflect the practical reality that a single species could not serve all price points.

Subsequent additions

The list has been formally extended on two notable occasions. In 2002, the AGTA and Jewelers of America added tanzanite as a December alternate, recognising the species' commercial prominence since its 1967 discovery in Tanzania. In 2016, the same two bodies added spinel as an August alternate alongside peridot, reflecting growing market interest in fine red and pink spinel from Burma, Vietnam, and Tajikistan. These additions are now widely accepted in the trade, although some retailers continue to use the 1912 list unmodified for its historical fidelity.

Position relative to other birthstone traditions

The Modern American list is one of several birthstone traditions in current use. The British National Association of Jewellers maintains a parallel list with some differences (notably, garnet for January as in the American list, but with separate handling of June and October). Indian and Tibetan traditions assign gems to days of the week and to planets in a Vedic system that does not map cleanly to the Western calendar. Buyers should treat the Modern American list as the dominant North American convention rather than a universal standard.

Commercial implications for the trade

The birthstone list functions as a powerful marketing scaffold for the retail jewellery year. Each month's stone receives a predictable bump in dealer interest, retail merchandising, and gift-giving promotion, with peaks in May (graduation, mothers), June (weddings, brides), and December (holiday). Jewellers structure inventory cycles around the list, and the addition of tanzanite to December and spinel to August reflected as much commercial interest as taxonomic ones — both species' producers had lobbied for inclusion as a way of boosting recognition and sales.

The list is also a source of customer education. Many first-time fine-jewellery buyers approach the trade through a birthstone gift, and the list provides a familiar entry point for explaining the species behind the assignment, the value drivers within each species, and the alternatives within a budget. For Skyjems and other coloured-stone specialists, the list is a yearly rhythm to plan around rather than a constraint to work within.

Further reading

• American Gem Society — birthstone list and history
• AGTA — birthstone announcements and additions
• Jewelers of America — birthstone reference
• GIA — birthstone reference