Sotheby’s Prepares Hong Kong Auction for Rare 28.88-Carat Flawless Jwaneng Diamond

Sotheby’s Hong Kong will auction the flawless 28.88-carat Jwaneng diamond on April 23, 2026, amid a shifting market for high-value natural stones and jewelry.

By: AXL Media

Published: Apr 9, 2026, 10:52 AM EDT

Source: WWD

The High-Value Transaction in Hong Kong

The Jwaneng 28.88 represents a pinnacle of luxury assets heading to the auction block this spring. Discovered at the Jwaneng mine in Botswana and developed by De Beers, the 28.88-carat round brilliant diamond was meticulously crafted from a 114.83-carat rough stone. Sotheby’s estimates the final hammer price will fall within the $2.2 million to $2.8 million range. The sale, part of the Live High Jewelry event, will also feature other significant stones from the same Botswana origin, signaling a concentrated effort to move high-grade inventory in the Asian market.

Shifting Dynamics in the Global Diamond Market

This high-profile sale occurs against a backdrop of significant volatility for the gemstone industry. Recent data indicates that the diamond index value plummeted by 11.5 percent between March 2025 and March 2026. Market analysts observe that natural stones have lacked positive monthly growth since mid-2025. This downturn is attributed to several factors, including the mass distribution of lab-grown alternatives and the increased cost of precious metals, which has pressured the overall retail price of fine jewelry.

Strategic Positioning of Ultra-Rare Assets

Despite the broad market decline, a clear divergence is emerging between standard commercial stones and elite investment-grade assets. The Jwaneng 28.88 is classified as a "Type IIa" diamond, a designation reserved for the most chemically pure stones, which account for less than 2 percent of global production. By bringing such a "vanishingly rare" asset to auction, Sotheby’s and De Beers are testing the resilience of ultra-high-net-worth demand. This strategy leans on the historical trend where exceptional cut, clarity, and provenance often shield assets from the inflationary or deflationary pressures affecting smaller, more common stones.