The 9.51-carat “Mellon Blue” diamond sold for $25.5 million at Christie’s Geneva Magnificent Jewels auction, held Tuesday at the Four Seasons Hotel des Bergues. The fancy vivid blue pear-shaped ...

Christie’s will offer “The Mellon Blue,” a diamond that boasts rarity, exceptional quality and important provenance. It is the first release and no doubt the top lot at Christie’s Geneva Magnificent ...