The US Mint's Gold Buffalo Coin is a .9999 pure, 24-karat gold bullion coin.  Prior to its inception in 2005, the American Gold Eagle coin, which is 22-karats, was the only official U.S. gold bullion coin.  In order to compete with 24-karat bullion coins minted by other governments, such as the Canadian Gold Maple Leaf coin and the Chinese Gold Panda coin, the American Gold Buffalo coin was legislated in 2005 and first minted in 2006.