De Beers and Sotheby's Unveil Rare 28.88-Carat Jwaneng Diamond Before Hong Kong Auction

At a London preview today, De Beers and Sotheby's placed one of the natural diamond world's most coveted recent discoveries before an audience of collectors and connoisseurs: the Jwaneng 28.88, a roughly 28.88-carat Type IIA stone that will head to auction at Sotheby's Hong Kong Luxury sales on April 23, 2026.

The name alone carries weight. Jwaneng, Botswana's celebrated diamond mine, is widely regarded as the richest diamond mine on earth by value, and Type IIA is the rarest classification in gemology, reserved for stones with virtually no nitrogen impurities. Fewer than two percent of all gem diamonds qualify. The designation typically signals exceptional colorlessness and transparency, a purity that allows light to move through a stone with almost unsettling clarity. At just under 29 carats, the Jwaneng 28.88 sits at a scale where that optical character becomes genuinely theatrical.

De Beers' decision to partner with Sotheby's for this sale reflects a broader recalibration in how the diamond industry presents extraordinary rough and polished stones to the market. Rather than moving the piece through traditional trade channels, the collaboration stages the diamond as an event, inviting the kind of cultural attention more typically associated with Old Master paintings or rare wristwatches. The London preview is part of that choreography: building anticipation across two of the world's most significant luxury capitals before the hammer falls in Hong Kong.

The April 23 auction date places the Jwaneng 28.88 squarely within a Hong Kong luxury calendar that has reasserted itself as a primary venue for record-setting gemstone sales. For a stone of this classification, the room it sells in matters as much as the stone itself.