The list below explores five of the world's largest gem-quality diamonds by carat weight.
The Cullinan Diamond
Discovery: The Cullinan diamond was discovered near Pretoria, South Africa, in 1905. Before it was cut and polished, the original stone weighed 3,106.75 carats and was 4.1 inches long.
Famous for: The rough diamond was cut into 105 diamonds, with nine large and 96 small stones. The largest of the nine diamonds is the Cullinan I, or the Star of Africa, weighing 530.4 carats, making it the world’s largest cut and polished white diamond. The Star of Africa and the rest of the diamonds cut from the original Cullinan belong to the British Crown Jewels.
Value: The Cullinan is estimated to be worth USD 400 million.
Learn more about the Cullinan diamond at Royal Collection Trust.
New Discovery: The Karowe Giant
Discovery: In August 2024, Lucara Diamond Corp. unveiled an extraordinary discovery from the Karowe mine in Botswana: a breathtaking 2,492-carat diamond. Unearthed from the EM/PK(S) section of Karowe’s south lobe, this colossal diamond was retrieved intact using cutting-edge X-ray transmission (XRT) technology, emphasizing Lucara’s innovative approach to diamond recovery.
Famous for: This gem is hailed as one of the largest stones ever recovered and the biggest since the legendary Cullinan Diamond.
Value: Unknown
Learn more about Karowe at the Washington Post.
The Excelsior Diamond
Discovery: The Excelsior was discovered on June 30, 1893, in the Jagersfontein Mine located in South Africa.
Famous for: This gem had a bluish-white tone and weighed 971 carats. Unfortunately, its discovery was not widely publicized in British newspapers due to the expiration of the mining company's contract and the purchase of the London firms on the same day as the stone’s discovery. The stone was cut into ten gems weighing 13 to 69 carats each. For unknown reasons, a single large piece was never produced from the rough stone. It was cut into small gems of assorted shapes bought by different buyers.
Value: The largest stone cut from the Excelsior diamond, weighing 69.68 carats, was sold in 1996 for $2,646,000. The other smaller stones were used to make fine jewelry, such as bracelets and tiaras.
Learn more about the Excelsior diamond at Wikipedia.
Star of Sierra Leone
Discovery: The Star of Sierra Leone was discovered in the Diminico mine in Sierra Leone in February 1972.
Famous for: The Star of Sierra Leone is the world’s fourth-largest and best gem in quality and the largest diamond discovered in an alluvial mine. It is also known for its perfect chemical purity and lack of plastic distortions in its crystal. The stone was first cut into an emerald shape, weighing 143.2 carats, but had to be re-cut into 17 diamonds that met the perfect cut scale. The largest stone of the Star of Sierra Leone weighs 53.96 carats and is cut in a flawless pear shape. Six smaller diamonds were made into a famous brooch called the “Star of Sierra Leone” by the jeweler Harry Winston.
Value: In 1972, the initial cut of Star of Sierra Leone was sold to Harry Winston for around USD 2.5 million.
Learn more about the Star of Sierra Leone.
The Incomparable Diamond
Discovery: In the 1980s, the Incomparable was discovered in a pile of rubble in Mbuji Mayi, Democratic Republic of Congo. The rough stone weighed 890 carats.
Famous for: The extraordinary color of the Incomparable showed varying shades of pale yellow to amber. The biggest cut produced a diamond of 407.48 carats, graded as internally flawless clarity. The Incomparable appeared in an auction in London and then in New York in 1988. It is the biggest diamond to be offered for sale in public but was never sold as the bidding did not reach the seller’s reserved price of USD 20 million. However, it is currently set in the famous Mouawad L’Incomparable Necklace, valued at over $55 million.
Value: Estimated at USD 55 million.
Learn more about Incomparable Diamond at the GIA.
