A rare 37-carat square emerald has set a new record as the world’s most expensive green stone, selling for nearly $9 million (£7 million) at an auction in Geneva.

In 1960, Prince Sadruddin Aga Khan commissioned Cartier to create the brooch, featuring the emerald set alongside 20 marquise-cut diamonds, for his then-wife, British socialite Nina Dyer.

Following their brief marriage, Dyer auctioned off the emerald in 1969 to raise funds for animal welfare.

The piece was later acquired by jeweler Van Cleef & Arpels, and eventually made its way to Harry Winston, the renowned “King of Diamonds” in the United States.

Max Fawcett, Christie’s EMEA Head of Jewellery, commented on the sale, stating, “Emeralds are in high demand right now, and this one meets all the criteria.”

He added that an emerald of such exceptional quality appears at auction only once every five to six years.

The previous record for a green stone was set by an emerald from Elizabeth Taylor’s iconic jewelry collection, which sold for $6.5 million during an auction in New York.