The coin, with a face value of $20 and distinctive design of an American eagle in flight on one side and Liberty striding forward on the other, was the last gold coin struck for circulation in the United States.
A 1933 Double Eagle gold coin sold for a record-setting $18.9 million at auction in New York and the world's rarest stamp went for $8.3 million.
The coin, the only 1933 Double Eagle ever allowed to be privately owned, was expected to sell for between $10 million and $15 million at the Sotheby's auction on Tuesday.
It was sold by shoe designer and collector Stuart Weitzman, who acquired it in 2002 for what was then a world record price of $7.6 million.
The coin was never issued after President Franklin Roosevelt took the United States off the gold standard and all copies were ordered destroyed.
In pictures: The "Double Eagle", one of the last US gold coins made for circulation, sold for a record $19.51M at an auction held by Sotheby's in New York, breaking the record for the most expensive coin in the world pic.twitter.com/g9F1xxrHbF— TRT World Now (@TRTWorldNow) June 8, 2021
Weitzman on Tuesday also sold a British Guiana One-Cent Magenta stamp, issued in 1856, for $8.3 million, confirming its place as the most valuable stamp in history.
The stamp is the only surviving one from a series that was printed by the South American nation because of a shortage of stamps sent over by its then British colonial rulers.
The designer had bought it in 2014 for $9.5 million and continued a tradition started by previous owners by adding his own flourish - a line drawing of a stiletto shoe and his initials - to the back of the stamp.
The buyers of the two items wished to remain anonymous, Sotheby's said.
In addition, a plate block of the 24 cent Inverted Jenny stamp, which was issued in 1918 for the first US air mail letters, sold for $4.9 million. It is the most valuable US stamp.
The Inverted Jenny, which was last sold at auction some 26 years ago for $2.9 million, is a collector's item because of a printing error in which its biplane design appears upside down.
Sotheby's said the stamp block, which sold below its pre-auction estimate, was bought by David Rubenstein, a co-founder of private equity company The Carlyle Group.
Weitzman, who has been collecting stamps and coins since boyhood, has said he will use the money from Tuesday's sale to fund his charitable ventures including medical research, his design school, and a Jewish museum in Madrid.
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