A rare square 37-carat emerald owned by the Aga Khan fetched nearly nine million dollars at auction in Geneva on Tuesday, making it the world's most expensive green stone.
Sold by Christie's, the Cartier diamond and emerald brooch, which can also be worn as a pendant, dethrones a piece of jewellery made by the fashion house Bulgari, which Richard Burton gave as a wedding gift to fellow actor Elizabeth Taylor, as the most precious emerald.
