World's most expensive green stone sells for whopping $9 million

A rare square 37-carat emerald has been sold for nearly $9million (£7million) at auction in Geneva, making it the world's most expensive green stone.

The Cartier diamond and emerald brooch owned by the Aga Khan,, dethrones a piece of jewellery made by fashion house Bulgari - given by Richard Burton as a wedding gift to Elizabeth Taylor. 

In 1960, Prince Sadruddin Aga Khan commissioned Cartier to set the emerald in a brooch with 20 marquise-cut diamonds for British socialite Nina Dyer, who he was briefly married to. 

Dyer then auctioned off the emerald to raise money for animals in 1969.

It was bought by jeweller Van Cleef & Arpels before passing a few years later into the hands of the United States' Harry Winston, nicknamed the 'King of Diamonds'.

'Emeralds are hot right now, and this one ticks all the boxes,' said Christie's EMEA Head of Jewellery Max Fawcett.

'We might see an emerald of this quality come up for sale once every five or six years.'

Also set with diamonds, the previous record-holder fetched $6.5million at an auction of part of Hollywood legend Elizabeth Taylor's renowned jewellery collection in New York.