The American $20 gold coin, better known as the Double Eagle, was minted in the United States from 1849 through 1933. There were two main designs, the Liberty Head and the St. Gaudens.
 

Liberty Head (Coronet) $20 Gold Coin

 
The Liberty Coronet design was used from 1849-1907, though there were only two specimens minted in 1849. One belongs to the Smithsonian Institution and the other's whereabouts are unknown. There are three major types of the Liberty design.
 
  1. -no motto, value "Twenty D." 1849–1866
  2. -with motto, value "Twenty D." 1866–1876
  3. -with motto, value "Twenty Dollars" 1877–1907
 

St. Gaudens $20 Gold Coin

 
Beginning in 1907 and continuing until 1933, the design used for the Double Eagle was created by the noted sculptor, Augustus St. Gaudens. The coin is considered by many to be the most beautiful United States coin. There were also three major varieties of the Saint Gaudens Double Eagles.
 
  • -High Relief, Roman Numerals, no motto 1907
  • -Low Relief, Arabic Numerals, no motto 1907–1908
  • -Low Relief, Arabic Numerals, with motto 1908–1933
 
The high relief was the first minted, but the coins needed to be struck eleven times to bring out the relief and then they didn't even stack correctly, so the low relief version was brought out later in 1907. Only about 11,000 high relief Double Eagles were minted and today they bring prices many times that of the more common varieties.