A rare blue diamond has sold for a record 10.5 million Swiss francs ($9.5m; £6.2m) at auction¹ in Geneva.

日内瓦拍卖会上，一块罕见的蓝宝石被卖出1050万瑞士法郎的新纪录。

It weighs 7.03 carats（克拉）, is smaller than a penny piece, and is one of only a handful of blue diamonds in existence.

The anonymous²（匿名的） phone bidder³ has yet to name the gem⁴（宝石）, mounted（安装） on a platinum⁵（白金） ring, auctioneers Sotheby's said.

The diamond was found in Cullinan mine in South Africa last year, and its clarity（清晰，透明） was graded as flawless - the highest designation.

Auctioneer David Bennett said: "It is a new world record price for a blue diamond."

It had a pre-sale catalogue estimate of 6.8 million to 10 million francs, excluding commission.

'Beyond beautiful'

The hammer price excluding commission was 9.3 million francs.

The scarcity⁶（缺乏，不足） of the gems⁷ is in part down to the fact so few places in the world mine for blue diamonds.

Mr Bennett said: "For people who are looking to buy something that nobody else has, or somebody who wants something that is beyond beautiful, a blue diamond is going to be very difficult to find, so when they appear on the market, you have to have a go."

The stones get their colour when the chemical boron（硼） is present during formation.

In May 2008 a 3.73 carat diamond was sold by Sotheby's at auction for nearly $5m (£3.4m) setting the world record price per carat for any gemstone at auction.