As our largest circulating coin, the Double Eagle or $20 Gold Piece has always held a special fascination for collectors and investors alike. Composed of nearly an ounce of gold, these big heavy coins never fail to impress. Because the Double Eagle did not appear until 1850, the type set consists of only six coins, in two major types. The three Liberty pieces, which thanks to the several shipwrecks, are now all available in high grade, and three Saint Gaudens designs. Only the High Relief is extremely costly. It's not particularly hard to find, it's just expensive due to its high demand.