The short answer
There is no single legal or scientific authority. The US list was adopted by the jewelry trade in 1912 and has been updated by trade groups since. Today the American Gem Society and GIA both publish month by month lists, and they agree on the main stones.
How the list changed
- 1912: The National Association of Jewelers (now Jewelers of America) adopted a standard US list at its meeting in Kansas City.
- 1952: The Jewelry Industry Council of America updated the list, adding alexandrite (June), citrine (November) and pink tourmaline (October), and replacing lapis lazuli with zircon in December.
- 2002: The American Gem Trade Association added tanzanite for December.
- 2016: The American Gem Trade Association and Jewelers of America added spinel for August.
Why some months have more than one birthstone
Extra stones were added to give more choice of color and price. In 1952, for example, alexandrite joined pearl in June and citrine joined topaz in November. Spinel was added for August in 2016, and tanzanite for December in 2002.
The traditional list
Before 1912, lists varied from country to country. The traditional stones, used from roughly the 15th to the 20th century, included bloodstone and jasper for March, agate for May and onyx for July. See the full traditional column on our birthstone chart.
Sources: Wikipedia: Birthstone (history of the US list); National Jeweler: JA, AGTA add spinel as August birthstone; American Gem Society: Birthstones. Checked October 16, 2026.
