Sotheby’s to auction rare 28.88-carat Jwaneng diamond in Hong Kong

A thin diamond ring can look almost architectural when the stone is this clean: Sotheby’s will offer a 28.88-carat, D-color, internally flawless Jwaneng diamond in Hong Kong, and its appeal lies in restraint as much as rarity. The stone, classified as Type IIa, belongs to a category that accounts for fewer than 2% of natural diamonds, a detail that explains why its surface reads with such unnerving calm.

That visual clarity began far from the sales room. The diamond was cut from a 114.83-carat rough discovered at Botswana’s Jwaneng Mine, then shaped through months of study and planning by De Beers’ master specialists. The result is the kind of stone that makes a bezel setting look almost modernist and a prong setting feel less decorative than structural: every choice around it has to justify itself, because the diamond offers no distraction.

Sotheby’s has placed the stone in its Hong Kong Luxury Week schedule for the live High Jewelry sale on April 23, with an estimate of HK$17 million to HK$22 million, or roughly $2.2 million to $2.8 million. De Beers and Sotheby’s introduced the Jwaneng 28.88 in London in March, ahead of the auction, as part of a collaboration meant to frame exceptional diamonds as works of art rather than trophies.

Quig Bruning, Sotheby’s head of jewels for the Americas and EMEA, called the stone “a vanishingly rare feat of nature” and “a masterclass in diamond cutting and polishing.” The language is apt, but the more interesting lesson is visual. In minimalist jewelry, the most persuasive diamonds are often the ones that do not need ornament to announce themselves. A well-cut solitaire, a pair of precise studs, or a narrow band set with one exceptional stone all depend on the same principle the Jwaneng 28.88 embodies: purity sharpens line.

The mine behind it adds another layer of weight. Debswana says Jwaneng Mine, in south-central Botswana, became fully operational in August 1982 and is one of the richest diamond mines in the world by value, contributing about 60% to 70% of Debswana’s total revenue. Sotheby’s is also expected to offer additional De Beers diamonds from the same mine in Hong Kong, including at least two other D-flawless lots: a 3.03-carat pear-shaped solitaire ring and a pair of earrings each set with a 2-carat round diamond. Together, they turn rarity into a study in proportion, proving that in high jewelry, the quietest stones can leave the deepest impression.