They are a girl’s best friend and one of them has just been bought for the equivalent of eleven million euros. It makes the 84.37 carat white diamond the second most expensive stone ever to be sold at auction. The unmounted jewel was bought by Georges Marciano, the American-based founder of the clothes firm Guess? He has named it Chloe, after his 12-year-old daughter. The precious stone sold for 18.193 million Swiss francs at Sotheby’s in Geneva.