Pearls that once belonged to the last Queen of France, Marie Antoinette, are expected to fetch up to £ 400,000, or about $827,000 Cdn at auction Wednesday.

Christie's auction house in London said Antoinette gave the pearls and diamonds to the Countess of Sutherland, Elizabeth Leveson-Gower, for safekeeping shortly before her family's unsuccessful attempt to flee France during the French Revolution in 1791.

"Prior to Lady Sutherland’s departure, as part of the embassy’s hurried withdrawal in August 1792, Marie Antoinette gave Lady Sutherland a bag of pearls and diamonds for safe keeping," Christies said in a release.

"Anyone caught in possession of this jewelry risked severe punishment. However, the wife of the British ambassador had diplomatic immunity and was one of the few who could be trusted to return the jewels when the Queen escaped, a plan which was never to be realized."

Antoinette was beheaded in 1793.

The pearls and diamonds were later used to fashion an extravagant wedding necklace when the countess' grandson married in 1849. The necklace has remained in the same family for over 200 years, according to the auction house.