RAPAPORT... A blue diamond weighing 5.53 carats failed to find a buyer at Sotheby’s Geneva on Wednesday despite being billed as the star of the auction. The cushion brilliant-cut, fancy-vivid-blue diamond is part of an eight-piece group called the De Beers Exceptional Blue Collection, which Sotheby’s has spread between its various Magnificent Jewels sales. No bids matched the stone’s threshold pri...
