The Centenary Diamond is the third-largest diamond ever recovered from De Beers’ Premier mine in South Africa.
Mined in 1986, the stone weighed 599 carats in its rough form. The discovery of the Centenary Diamond was announced in 1988 on the occasion of the mining giant’s 100th anniversary celebrations, which also gave the diamond its name, “Centenary Diamond.”
De Beers’ website reports that one of the world’s best diamond cutters, Gabi Tolkowsky, was entrusted with the task of cutting and polishing the Centenary Diamond. The work itself took place in a specially constructed room at the De Beers Diamond Research Laboratory.
The first step involved in Centenary Diamond polishing – the removal – by hand – of 20 carats of the rough diamond’s mass, a delicate process that took 154 days. After the original paring down, Tolkowsky and his assistants created 13 sketches of possible cuts and presented them to the De Beers board, which eventually selected a modified heart shape for the Centenary Diamond.
The final cutting of the Centenary Diamond, which lasted close to a year, left a modified heart-shaped diamond of 273.85 carats with an unprecedented 247 facets and two flawless separate pear-shaped diamonds.
The Centenary Diamond measures 39.90 X 50.50 X 24.55m. The Gemological Institute of America has certified the diamond’s color as D and its clarity as internally and externally flawless. While the stone has never been officially valued, it was insured for $100 million when it was officially unveiled in May 1991.
According to some reports, the Centenary Diamond was sold in June 2008, although De Beers has declined to confirm or deny the rumors.