This Rare Gem Could Sell for $50M

Tuesday's the day for the "Bleu Royal," the biggest internally flawless fancy vivid blue diamond ever to go on the auction block. That's when the rare 17.6-carat gem, currently set in a ring, will be up for grabs in Geneva via Christie's, where it's expected to sell for up to $50 million, reports CNN. The diamond—deemed "the largest of its kind" by Rahul Kadakia, Christie's international head of jewelry—is being sold as part of the auction house's "Magnificent Jewels" sale, which includes "a curated selection of historic and modern [jewelry] from all periods," and from the most well-known jewelry purveyors, including Harry Winston, Cartier, and Van Cleef & Arpels, per Arts & Collections.

That magazine explains that blue diamonds are among the rarest gemstones on the planet, forming at depths of more than 400 feet below the surface. They're said to gain their blue hue from the chemical element boron, which can be found deep in the Earth's mantle. Christie's previous record for a blue diamond was in 2016, when it sold a rare 14.6-carat gem called the "Oppenheimer Blue" for $57 million, per CNN. "We hope it will beat the Oppenheimer," Kadakia says. "We have toured it all around the world, to Asia, to the US and Europe, and we've had good interest from collectors worldwide." (More diamonds stories.)