$20 Gold Liberty (aka Double Eagles)
A Gold Double Eagle is a gold coin of the United States with a denomination of $20. Although the "eagle"-based nomenclature for gold U.S. coinage is often assumed to be a nickname, the "eagle," "half-eagle" and "quarter-eagle" were specifically given these names in the Act of Congress that originally authorized them ("An Act establishing a Mint, and regulating Coins of the United States", section 9, April 2, 1792). Likewise, the Double Eagle was specifically created as such by name ("An Act to authorize the Coinage of Gold Dollars and Double Eagles", title and section 1, March 3, 1849).
The first gold double eagle was minted in 1849, coinciding with the California Gold Rush. In that year, the mint produced one such gold coin, which now resides in the Smithsonian Institution in Washington DC. In 1850 regular production began. Prior to that time, gold eagles with a denomination of $10 were the largest denomination of US gold coin. $10 gold eagle coins were produced beginning in 1795, just two years after the first U.S. mint opened. Since the $20 gold coin had twice the value of the gold eaglecoin, these coins were designated "double eagles".