The 18th-century necklace containing approximately 300 carats of diamonds had been estimated to sell at the Sotheby’s Royal and Noble Jewels sale for $1.8-2.8m.

The final price was agreed after an exciting bidding battle. 

Some of the diamonds in the piece are believed to originate from the jewel at the centre of the Affair of the Diamond Necklace – a 1780s scandal that worsened Marie Antoinette’s reputation and increased support for the French Revolution, the Guardian reports. 

The necklace had been passed down generations from various French aristocratic families, and is believed to have been worn twice in public, including at the 1937 coronation of King George VI and once at Queen Elizabeth II’s coronation in 1953.