The world's most expensive coin

Nearly half a million of the US 'Double Eagle' gold twenty dollar coins were originally minted during the Great Depression, but now only 13 are known to be in existence today. 

A 'Double Eagle' gold twenty dollar coin is displayed above a catalogue picture showing the reverse side of the coin at Goldsmith's Hall on March 2, 2012 in London, England. Nearly half a million of these coins were originally minted in the midst of the Great Depression in the US. Only 13 are known today after the rest were melted down before they ever left the US Mint, sacrificed as part of a strategy to stabalise the American economy. In 2002 a Double Eagle sold at auction for $7.6 million.