What Is the Largest Rough Diamond in the World
The largest rough gem-quality diamond ever recorded is the Cullinan, a 3,106.75 carat stone discovered in South Africa in 1905, and it remains the benchmark for all subsequent large rough finds according to Forbes. The stone was unearthed at the Premier Mine in Cullinan, Transvaal, and its size, clarity, and lack of visible flaws made it an immediate global sensation.
In terms of weight, the Cullinan is followed by the Lesedi La Rona, a 1,109 carat rough stone recovered in Botswana in 2015, and the Excelsior, a 995 carat diamond found in South Africa in 1893 Britannica notes. These three stones are consistently cited in mining and gemological records as the largest rough diamonds ever recovered, with the Cullinan retaining the top position.
Where Was the Largest Rough Diamond Found
The Cullinan was discovered at the Premier Mine, now owned by Petra Diamonds, in what is now the Cullinan town of Gauteng province, South Africa Petra Diamonds confirms. The mine is a kimberlite pipe known for producing large, high-quality type IIa diamonds, and the Cullinan was extracted from a single heavy blue ground mass on January 26, 1905.
Geologically, the stone formed over billions of years under extreme pressure and temperature in the Earth's mantle, and its transport to the surface was driven by volcanic kimberlite eruptions. The Premier Mine remains active and continues to produce notable stones, though no single rough has yet approached the Cullinan's record size.
Who Owns the Largest Rough Diamond and What Happened to It
The Transvaal government purchased the Cullinan rough and presented it to King Edward VII for his 66th birthday in 1907, and the stone was later cut and polished by Asscher Brothers in Amsterdam Sotheby's records. The largest polished gem, Cullinan I or the Great Star of Africa, weighs 530.2 carats and is mounted in the Sovereign's Sceptre with Cross, part of the British Crown Jewels held at the Tower of London.
Today, the polished Cullinan diamonds are owned by the British Crown and are not part of any private or commercial collection, while the rough stone itself no longer exists as a single piece. The legacy of the Cullinan continues to shape the diamond industry, influencing how large roughs are valued, cut, and marketed by major miners and auction houses worldwide.