WORLD’S MOST EXPENSIVE COLORED DIAMONDS Sun-Drop Diamond ($10.9 million) Setting a record for a yellow diamond at auction, the Sun-Drop Diamond of South Africa sold at Sotheby's Geneva this week for more than $10.9 million. The pear-shaped gem weighs 110.3 carats and was discovered only last year, meaning it has no previous owners, which added to its value. And it also comes with a bonus—the new owner gets to name the stone.