Stunning 36.92-Carat Blue Diamond Recovered From Botswana’s Karowe Mine

A remarkable new discovery from Lucara Diamond Corp. is turning heads across the jewelry world: a 36.92-carat high-quality blue diamond recovered from the famed Karowe Mine in Botswana. For collectors and connoisseurs, the real excitement lies in what this rough crystal could become.

Based on typical cutting yields of 30% to 40%, the stone could produce a polished “hero” diamond in the range of 11 to 15 carats. That size places it in the company of some of the most celebrated blue diamonds ever sold at auction, such as the 14.62-carat Oppenheimer Blue and the 15.10-carat De Beers Blue — gems that achieved prices north of $50 million. If the Karowe rough delivers comparable color and clarity, it could one day join this elite group.

Not only is the rough stone exceptionally large, but it also belongs to the ultra-rare Type IIb category — a classification representing less than half of one percent of all natural diamonds.

Blue diamonds are extraordinarily rare because of the unusual conditions required to form them. Their mesmerizing color comes from trace amounts of boron trapped within the diamond’s carbon structure — a chemical anomaly that occurs only under highly specific conditions deep within the Earth. Scientists believe these diamonds form as much as 400 miles below the surface, far deeper than most other diamonds, making their journey to the surface even more remarkable.

The source of this latest find is just as noteworthy. The Karowe Mine has earned a global reputation for producing exceptional diamonds, including eight of the 10 largest rough diamonds ever discovered. Legendary stones such as the 1,758-carat Sewelô and the 1,109-carat Lesedi La Rona underscore Karowe’s unique ability to yield massive, high-value gems.

Interestingly, this latest blue diamond wasn’t recovered from freshly mined ore, but from previously processed stockpile material. The find was made with the assistance of Lucara's advanced X-ray technology. The X-ray Transmission (XRT) sorting system scans material using high-energy X-rays to detect differences in atomic density. Because diamonds are less dense than the surrounding rock, the system can identify them even when they are completely hidden from view. Once detected, precise air jets separate the stones and divert them into a secure collection chamber.

This process is especially important at Karowe, where preserving large, high-value diamonds is critical. Unlike traditional crushing methods, XRT allows for early recovery, reducing the risk of breaking extraordinary stones during processing.

In this case, the technology proved invaluable — rescuing a rare blue diamond that might otherwise have gone unnoticed.

Credit: Image courtesy of Lucara Diamond.