A 15.1-carat blue diamond is expected to fetch at least $48 million when it goes to auction in April in Hong Kong, Sotheby’s announced Wednesday. Known as the De Beers Cullinan Blue, the gem is the largest diamond with a fancy vivid blue grade to head to auction, according to the auction house. The Gemological … Continue reading 15.1 Carat Diamond Set To Sell For At Least $48m