The 1933 Double Eagle

The 1933 double eagle (United States 20-dollar gold coin) currently holds the record for highest price paid at auction for a single U.S. coin when it was purchased for US$7.59 million. 445,500 specimens of this Saint-Gaudens Double Eagle were minted in 1933, the last year of production for the Double Eagle, but no specimens ever officially circulated and nearly all were melted down, due to the discontinuance of the domestic gold standard in 1933.
Production of the 1933 double eagle
In order to end the 1930s general bank crisis, U.S. president Franklin D. Roosevelt issued Executive Order 6102 in 1933 and the Gold Reserve Act in 1934, which outlawed the circulation and private possession of United States gold coins for general circulation, with an exemption for collector coins. This act declared that gold coins were no longer legal tender in the United States, and people had to turn in their gold coins for other forms of currency. The 1933 gold Double Eagles were struck after this executive order, but because they were no longer legal tender, most of the 1933 gold coins were melted down in late 1934 and some were destroyed in tests. Two of the $20 double eagle were presented by the United States Mint to the U.S. National Numismatic Collection, and they were recently on display in the "Money and Medals Hall" on the third floor of the National Museum of American History.
These two coins should have been the only 1933 Double Eagle coins in existence. However, unbeknownst to the Mint, a number of the coins (20 have been recovered so far) were stolen, possibly by the U.S. Mint Cashier, George McCann. At least nine of these coins, which were illegal to possess, found their way via Philadelphia jeweler Israel Switt, into the hands of collectors.
The coins circulated amongst collectors for several years before the Secret Service became aware of their existence. The matter came to the attention of Mint officials when an investigative reporter looked into the history of the coins and contacted the Mint as part of his research, as a result of which an official investigation was begun by the Secret Service in 1944. Seven of the coins were discovered and turned over to federal agents (or seized) within the first year of the investigation, with one coin remaining in public possession until 1952