Bids on the imperial consignment far outstripped pre-sale estimates. There were nine items from the collection of Napoleon's daughter Stephanie de Beauharnais as well as a sapphire crown which previously belonged to Queen Maria II of Portugal.

"The collection of Stephanie de Beauharnais (and Queen Maria II) took towards 2.7 million Swiss francs ($2.97 million) hammer (price) ... almost three times the pre-sale estimate," Max Fawcett, the head of Christie's jewellery department in Geneva, said. "There was huge demand from collectors around the world."

The nine items in the Beauharnais set, which were sold individually, included a necklace and tiara adorned with sapphires from mines in what was then known as Ceylon, now Sri Lanka. read more The jewels date back to the early 19th century and are believed to have been a wedding gift for de Beauharnais, who was adopted by Napoleon and his wife Josephine de Beauharnais.

The nine jewels were among 144 lots that went under the hammer on Thursday, achieving total sales of 57.8 million francs.

The crown of Portugal's Queen Maria II, set with a Burmese sapphire in the centre, fetched the highest bid among the ten imperial items at a realised price of 1.77 million francs, 10 times the lower end of its 170,000 - 350,000 franc pre-sale estimate.

Meanwhile, a D colour, Internally Flawless Rectangular step-cut diamond of 100.94 carats, estimated to sell for 12-18 million francs, closed at 12.84 million francs.

"We really saw that the appetite for top jewellery is still really strong in today's market," Fawcett said.