Gem Diamonds unearths 193-carat stone as Letseng prices hold firm

Gem Diamonds reported average prices of $1,288 per carat for the fourth quarter of 2025 at its Letseng mine in Lesotho, and disclosed the post-period recovery of a 193-carat white Type II diamond, underlining the mine's continued ability to produce exceptional stones even as the broader rough diamond market struggled.

The quarter saw 20,961 carats recovered and 21,191 carats sold, from 1.37 million tonnes of ore treated. For the full 2025 year, Letseng's production fell 14% to 90,354 carats from 105,012 carats in 2024, while the average price achieved across the year dropped 20% to $1,105 per carat as the broader downturn weighed on realisations even at one of the world's highest-value kimberlite mines.

Big stones keep the numbers respectable

Despite the tougher pricing environment, Letseng's flow of large, high-quality diamonds continued to support revenue. The mine's single highest-priced stone of the year, an 8.83-carat pink diamond, fetched $66,602 per carat, while six diamonds sold during the year for more than $1 million each generated a combined $9.2 million. Nine diamonds larger than 100 carats were recovered across the full year, against 13 the year before — a decline, but still a remarkable rate of large-stone discovery for a single mine.

Total sales value down 36%

Even so, the combination of lower volumes and weaker average pricing dragged total annual sales value down 36% to $97.7 million from $152.8 million in 2024, a reminder that even the world's premier producer of large, high-value diamonds could not fully escape the industry-wide downturn driven by lab-grown competition and soft Chinese demand.

What it means for Lesotho

Letseng, in which Gem Diamonds holds a 70% stake alongside the government of Lesotho, is often described as the highest dollar-per-carat kimberlite diamond mine in the world, and its performance is closely watched as a bellwether for the premium end of the natural diamond market. The 193-carat discovery, recovered just after the fourth quarter closed, offered an early sign that 2026 might bring more of the exceptional stones that have defined Letseng's reputation, even as prices for everyday goods remained under pressure.

Sources

• Gem Diamonds: Q4 2025 Trading Update, 04 Feb 2026

Photo: The Letseng diamond mine in Lesotho, the highest dollar-per-carat kimberlite mine in the world. Lschefa, Wikimedia Commons, CC BY-SA 4.0.