The historic fancy vivid blue diamond set to headline Christie’s Geneva sale next month could sell for up to $50 million.

The historic fancy vivid blue diamond set to headline Christie’s Geneva sale next month could sell for up to $50 million.

23-Carat ‘Golconda Blue’ Heads to Auction   Lauren McLemorelauren.mclemore@nationaljeweler.com At its upcoming Geneva jewelry auction, Christie’s will offer the 23.24-carat “Golconda Blue,” a rare blue diamond with more than 250 years of history and ties to...