Sotheby's expected the piece would sell for maybe one or two million but it sold for much more.
The buyer wants to remain anonymous.
The pendant is from the late monarch's private collection.
Stay on top of breaking news stories with the ABC11 News App
Sotheby's is calling it one of the most important royal jewelry collections to ever come to auction, with the pearl pendant setting a new auction record for a pearl.
The collection also included a diamond brooch, which sold for $2.1 million, and a monogram ring with woven strands of Antoinette's hair, which sold for $440,000.
A total of 100 items brought sold for more than $53 million.
A creative lie lands thieves thousands of dollars in Louis Vuitton merchandise from San Francisco store
VUITTON GONE: It was like a heist from a movie--a movie like "Ocean's Eleven." A plot that even makes a former FBI agent marvel at the thieves creativity that landed them thousands of dollars in Louis Vuitton merchandise.