What Is the World's Biggest Diamond?

Cullinan Diamond I
The Cullinan Diamond I comes from the world's largest uncut diamond gem called the Cullinan. (Image credit: diamondvues.com)

During a routine mine inspection in 1905, superintendent Frederick Wells discovered a 3,106-carat diamond in the Premier Mine in Pretoria, South Africa.

Dubbed the "Cullinan" after mine owner Sir Thomas Cullinan, the 1.33-pound precious gem was at the time the largest rough diamond ever found.

In 1908, the Cullinan was cut into about 100 pieces, resulting in nine large diamonds and many smaller siblings. The largest piece, called "Cullinan I" or "Star of Africa I," is 530 carats and is mounted in the British Sovereign’s Royal Scepter, on display in the Tower of London.

The second-largest stone — "Cullinan II" or "Star of Africa II" — is 317 carats and sits in another crown jewel, the Imperial State Crown. These two diamonds still rank among the top five largest cut diamonds.

Cullinan I was actually the world's largest faceted diamond in world until 1987, when the "Golden Jubilee" stole its title. This 545.67-carat diamond was cut from a 755-carat rough stone that was also discovered in the Premier Mine.

Interestingly, before being given its prestigious name, the Golden Jubilee was known simply as the "Unknown Brown."

Some of the other largest diamonds in the world include the "Incomparable" (407.48 carats), the "Spirit of de Grisogono" (312.24 carats) and the "Centenary" (273.85 carats).

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Joseph Castro
Live Science Contributor
Joseph Bennington-Castro is a Hawaii-based contributing writer for Live Science and Space.com. He holds a master's degree in science journalism from New York University, and a bachelor's degree in physics from the University of Hawaii. His work covers all areas of science, from the quirky mating behaviors of different animals, to the drug and alcohol habits of ancient cultures, to new advances in solar cell technology. On a more personal note, Joseph has had a near-obsession with video games for as long as he can remember, and is probably playing a game at this very moment.