An old mine-cut diamond brooch or pendant that was owned by Emperor Napoleon I circa 1810 is displayed as Sotheby's unveiled a selection of items on Nov. 6, 2025, in Geneva, Switzerland. Robert Hradil

A diamond brooch that French emperor Napoleon lost while fleeing from the Battle of Waterloo in the early 19th century sold for more than 3.5 million Swiss francs — about $4.4 million — at a Geneva auction on Wednesday, Sotheby's said.

The brooch, which can also be worn as a pendant, features an oval diamond weighing over 13 carats, surrounded by smaller cut diamonds.

"This historical and highly important diamond jewel was part of other personal belongings the Emperor had taken with him to Waterloo, including medals, weapons, silverware, a hat and a jewellery box containing dozens of loose diamonds as well as jewellery," Sotheby's said in a news release.

"In his haste to flee Waterloo, where his armies had been overwhelmed by the combined forces of the British and Prussian armies, Napoleon had to abandon some of his carriages when they got stuck in a muddy road a few miles away from the battlefield — including the carriage containing those precious belongings," it said.

The sale price vastly outstripped the high end of the pre-sale estimate of 200,000 francs. The hammer price was 2.85 million francs, excluding fees and other charges that were included in the final aggregate price.

Sotheby's did not disclose the identity of the seller, and said that the buyer was a "private collector."

The brooch and a few other items were offered to the Prussian King Friedrich Wilhelm III as battle trophies in 1815 three days after the Battle of Waterloo, according to Sotheby's. It remained among heirlooms of the Prussian Royal House of Hohenzollern for centuries and over the last few years was part of a different private collection.

Among dozens of lots on the auction block was a green beryl weighing over 132 carats, which Napoleon was said to have worn at his 1804 coronation. The jewel sold for a hammer price of 838,000 francs, or more than 17 times the high-end pre-sale estimate.

One diamond expert said the sale took on added allure in the wake of the robbery of Napoleonic jewels from the Louvre museum in Paris last month. The thieves made off with eight pieces in broad daylight and dropped one as they made their escape.

"Given the recent Louvre heist and the provenance of arguably the most famous French figure in history, I'm not surprised the jewel achieved a majestic 3.5 million francs," said Tobias Kormind, managing director of online jeweler 77 Diamonds. "The brooch arrives at a moment of renewed global fascination with Napoleonic jewels, and its story is irresistible."

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