What Is the Biggest Uncut Diamond in the World
The biggest uncut diamond in the world is the Constellation, a 910-carat Type IIa stone discovered in November 2015 at the Karowe Mine in Botswana by Lucara Diamond Corp. It remains the largest gem-quality uncut diamond ever recovered and a record holder in the global diamond industry. The stone was sold in a private transaction in 2024 to an undisclosed buyer through a structured tender process managed by the company.
Type IIa diamonds are the purest crystalline form of natural diamond, with minimal nitrogen impurities, and they typically command the highest per-carat value when cut. The Constellation is valued primarily for its exceptional size, clarity, and crystal structure, which gives cutters a rare opportunity to produce multiple large polished stones from a single rough piece.
How the Constellation Compares to Other Large Uncut Diamonds
Before the Constellation, the largest known uncut diamond was the Lesedi La Rona, a 1,109-carat stone recovered in 2015, also from the Karowe Mine by Lucara Diamond Corp. While Lesedi La Rona is heavier, it was cut into smaller polished gems, so the Constellation now holds the title of the largest intact uncut diamond available on the market.
Other notable large rough stones include the Excelsior Diamond, found in South Africa in 1893, and the Star of Sierra Leone, discovered in 1972, but both were cut into many smaller gems over time. The Constellation's combination of massive size and preserved rough condition makes it unique among high-value diamonds and a benchmark for future discoveries.
Why the Biggest Uncut Diamond Remains Uncut and Who Owns It
Preserving Value Through the Rough
Keeping a diamond uncut preserves its full carat weight and can maximize the total value of the rough, especially when the crystal is large and flawless. Cutting a 910-carat stone involves complex planning to optimize yield, color, and clarity across all resulting gems, and the owner may choose to retain the rough as a strategic asset rather than split it immediately.
Market Dynamics and Private Sales
Large rough diamonds like the Constellation are typically sold through private tenders rather than public auctions, with buyers including sovereign wealth funds, institutional investors, and major jewelry groups. The sale process is confidential, and the final price is rarely disclosed, though valuations for stones of this size can reach hundreds of millions of dollars depending on the buyer's strategic goals.
Lucara Diamond Corp's Role
Lucara Diamond Corp operates the Karowe Mine in Botswana and has recovered multiple record-breaking stones, including the 1,758-carat Sewelô in 2019 and the Lesedi La Rona. The company uses advanced X-ray transmission technology to identify large, high-value rough stones early in the processing stage, a method that has positioned it as a leader in the high-end diamond market.
Future Outlook for Record-Setting Rough Stones
New large diamond discoveries continue to emerge from Botswana, Russia, and Canada, but matching the Constellation's combination of size, clarity, and market readiness remains rare. The stone's sale and any future cutting plans will likely be closely watched by industry analysts, collectors, and investors tracking the ultra-high-end diamond segment.