A 6.16 carat, dark gray-blue Farnese Blue diamond, passed down through European royal families for 300 years, was auctioned off in Geneva for 6.7 million Swiss francs (HK$52.6 million), beating auctioneers Sotheby's estimate of up to five million Swiss francs.
The gem, which came 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.
The rare diamond did not stay in one place in Europe as it was passed down through more than seven generations.
And as their descendants married into other European families, it traveled from Spain to France, Italy and Austria.
Two other jewels went for even higher prices, also surpassing estimates.
An oval diamond 50.39-carat ring fetched 8.1 million francs, while a round brilliant-cut 51.71-carat diamond sold for 9.26 million francs.