By the start of yesterday, the collection left by Ms Harriman, who died in February while United States ambassador in France, had already attracted almost $7m (pounds 4.2m). The identity of most buyers was kept secret, but among them was the actress, Whoopi Goldberg.
"One of the interesting things about the collection is [Harriman] was really a citizen of three countries," said Sotheby's spokesman Matthew Weigman. "She was born in England, she lived in France for a long time and she became an American."
The main beneficiaries of the sale, which included many items from her Washington townhouse, will be her son, Winston Churchill, as well as his estranged wife, Minnie Churchill, who attended some of the sale sessions.
Among items that sold for much greater sums than expected was a four- poster bed. Valued by Sotheby's at $12,000 to $15,000, it was bought on Tuesday for $41,000. A copy of John F Kennedy's nuclear test ban treaty, estimated at $5,000 to $7,000, was sold to an unidentified European foundation for $46,000.
While the sale has seemed a tame sequel to the Jacqueline Onassis auction of last year, also held at Sotheby's, any sense of anti-climax has been offset by the handsome bids.
"When things go for 10 times or 15 times their bid, there is definitely an aura," said Diana Brooks, Sotheby's chief executive.
One happy bidder was a Chicago hairdresser, David Bradely, who had tried but failed to get into the packed Kennedy Onassis sale last year. He paid $1,995 for seven silver pieces owned by Harriman. "She is a piece of history," he said. "This is second best. She had a bunch of great stuff".
Ms Goldberg was reported to have bought a Picasso print, La Danse, for $4,600.