While certain months have only one birthstone choice, those brought into the world in August are adequately fortunate to have three. The advanced and conventional birthstones for August are peridot, spinel, and sardonyx. Referred to a few times in the Holy book, sardonyx is the most established August birthstone on record. It was one of the gems in the esteemed cleric’s breastplate (a forerunner to birthstones), and one of Jerusalem’s establishment stones.