Marie Antoinette's pearls expected to fetch £400,000

Sumptuous pearls which graced the neck of Marie Antoinette are to go on sale in London later this year with an expected asking price of £400,000.

The jewels were smuggled out of revolutionary France by Lady Elizabeth, the Countess of Sutherland, wife of the British ambassador and an ally of the wildly extravagant Queen Consort. Lady Elizabeth made a pact to return them to her friend once she had escaped from imprisonment.

But the wife of Louis XVI was never to secure her freedom and met her highly public end in front of a baying mob in the centre of Paris in 1793, her guillotined head paraded before the crowd as a proof of the fall of the hated monarchy.

Fifty years later on the other side of the Channel, 21 of the drop-shaped natural pearls were mounted on to a necklace for the wedding of Lady Elizabeth's grandson, George Granville William Sutherland-Leveson-Gower and Ann Hay McKenzie.

Raymond Sancroft-Baker, senior director of Christie's Jewellery, London, said: "It is exceptionally rare to be able to offer jewels that belonged to Marie Antoinette and which are completely fresh to the market.

"The story behind the pearls and their integral incorporation into this necklace for the Sutherland-Leveson-Gower family wedding in 1849 adds to its fascinating history."