Invest in the United States Mint Buffalo BU Gold Coin that consists of 1 oz gold, with a purity of .9999. This coin was minted in 2016. Its obverse side features the Buffalo Nickel design, depicting an American Indian, made famous by James Earle Fraser. On the reverse, it features an engraving of Black Diamond, a bison who resided at Central Park Zoo in the 1900s. In addition, this 50-dollar coin is 2.95 mm thick.