Ammon News - A 10-carat blue diamond which could fetch $20 million when it goes under the hammer later this month was presented by auction house Sotheby's in Geneva on Thursday.

The cushion-shaped piece, known as the "Mediterranean Blue Diamond," was mined in South Africa and displayed a rare colour that qualified as fancy vivid blue, Sotheby's said.

"The market for coloured diamonds continues to go from strength to strength," said Jessica Wyndham of Sotheby's, added that she expected a price in the region of $20 million.

In 2016, another vivid blue diamond sold for 56.8 million Swiss francs ($68.7 million) at a Christie's auction in Geneva.

Sotheby's high jewellery collection, which includes other coloured gemstones, was presented to journalists in Geneva ahead of a live auction scheduled for May 13 at the Mandarin Oriental Hotel. Reuters