The medal, which sold for more than five times the expected price,was the highest priced item in the morning session of the second day of the nine-day sale of items from the Duke and Duchess of Windsor's house in Paris.
Yesterday morning's sale of 114 items raised more than pounds 170,000 with the total for the auction so far topping pounds 1.3m.
The high point on the opening day of the auction on Thursday was when a 61-year-old piece of the duke and duchess's wedding cake sold for pounds 17,300. The cake - sealed in a three-inch-square white box - had been valued at just pounds 660.
Another highlight of the opening session of the auction was the sale of a portrait of the Duchess by the late British photographer Cecil Beaton. It had been valued before the sale at pounds 10,000 but was purchased for pounds 80,000.
More than 40,000 lots are being sold from the mansion in the Bois de Boulogne where the couple lived in exile after the abdication crisis in 1936.
The sale was arranged by Mohamed Al Fayed, the owner of Harrods store, who now owns the property which he claims was the destination of Diana, Princess of Wales, and his son Dodi on the night they died in a car accident.
Joe Friedman, an expert at Sotheby's New York, said: "This is the biggest auction we've ever held in the United States, and as a royal collection, more or less unprecedented in history. One has to go back to the 17th century to find anything comparable - the sale of the possessions of Charles I."Reuse content