A model poses with the "The Apollo Blue" diamonds (left), mounted as earrings, during a press preview by Sotheby's auction house, on May 11, 2017 in Geneva. The Farnese Blue diamond sold at auction in Geneva for US$6.7 million on May 15, 2018. (FABRICE COFFRINI / AFP)
The Farnese Blue diamond, which was passed down through European royal families for 300 years, sold at auction in Geneva on Tuesday for 6.7 million Swiss francs (US$6.7 million), beating auctioneers Sotheby's estimate of 3.5-5.0 million.
The 6.16 carat, dark grey-blue gem from the Golconda diamond mines of India was first given to Elisabeth Farnese, daughter of the Duke of Parma, in 1715 when she married Philip V of Spain.
It was passed down through more than seven generations and, as their descendants married into other European families, it travelled from Spain to France, Italy and Austria.
Two other jewels went for even higher prices, also eclipsing their estimates. An oval diamond ring weighing 50.39 carats went for 8.1 million francs, while a round brilliant-cut diamond weighing 51.71 carats sold for 9.26 million francs. (US$1 = 1.0017 Swiss francs)