The coin, known as a Flowing Hair Silver Dollar because it shows Lady Liberty with long, flowing locks, was minted in Philadelphia in 1794.
"It's one of the rarest coins in existence," said Laura Sperber, co-partner of Legend Numismatics of Lincroft, which purchased the coin. "Who knows who could have held this coin? George Washington? Any of the Founding Fathers?"
The (Newark, N.J.) Star-Ledger reported Tuesday there are only believed to be about 150 of the coins still in existence of the 1,750 minted that year before the mold was destroyed.
The coin was previously owned by Martin Logies, a private collector who purchased it for a then-record $7.8 million in 2010, which had stood as the record for a coin purchase until Legend topped it last week. It was the last of 94 lots, conducted last week by auction house Stack's Bowers in New York City.