The modern birthstone(s) for August are Peridot, Spinel, Sardonyx. Traditional birthstone(s) are Sardonyx, Carnelian. Zultanite — gem-quality color-change diaspore from Türkiye — is not an official August birthstone.
Modern birthstone
The modern August birthstone list, established by the American National Association of Jewelers in 1912 and updated periodically since, includes: Peridot, Spinel, Sardonyx.
Traditional birthstone
The traditional birthstone list (drawing from older European and Polish gem-month associations) for August includes: Sardonyx, Carnelian.
Where Zultanite fits
Not an official August birthstone, though Zultanite’s sage-green daylight color matches peridot in hue. Both gems are 6.5–7 Mohs and visually compatible.
How birthstone lists work
There is no single global authority on birthstones — modern, traditional, mystical (Tibetan), and Ayurvedic lists all differ. Zultanite was discovered too late (commercial production began in the early 2000s) to enter any of the historical lists.