The Centenary Diamond
Discovered on 17th July 1986 at the De Beers Premier Mine in Gauteng Province, South Africa, the rough stone from which the Centenary diamond was cut weighed some 599 carats. That makes it the twentieth largest rough diamond ever to come out of those mines. Once finished, it would become the world's sixth largest cut diamond. Its discovery couldn’t have been timed better for De Beers who were due to celebrate 100 years of operations in 1988. At a celebratory banquet on 11th March of that year, De Beers chairman, Julian Oglivie Thompson, announced the find to a stunned audience.
The man chosen to evaluate and subsequently cut the Centenary was Gabi Tolkowsky. Tolkowsky is famed in the diamond industry as one of the most accomplished cutters in the world and it was his great uncle, Marcel Tolkowsky, who is generally acknowledged as the father of the modern round brilliant diamond cut.
It took Tolkowsky and his team of master cutters, engineers and electricians, one whole year to assemble the conditions that would be necessary to cut the Centenary. In an underground room deep within the De Beers Diamond Research Laboratory in Johannesburg, South Africa, Tolkowsky took 154 days to remove 50 carats of unnecessary rough from the stone. This was achieved by hand cleaving the diamond, a laborious process which meant that the off cuts could be used rather than being lasered into oblivion. Indeed two flawless pear shaped stones weighing 1.47 and 1.14 carats were cut in addition to the finished Centenary.
D colour, flawless
Tolkowsky then proposed a total of thirteen different designs to the De Beers board who, on his recommendation, settled on a modified heart shape. In March 1990, faceting began, a process which was to last almost a year. The finished masterpiece weighed 273.85 carats, measured 39.90 × 50.50 × 24.55 mm, and had 247 facets - 164 on the stone and 83 around its girdle. It was certified by the Gemological Institute of America as being D colour, externally and internally flawless, the highest possible grades for both colour and clarity respectively. Mr. Nicholas Oppenheimer, then Deputy Chairman of De Beers, rightly declared, "Who can put a price on such a stone?", confirming that it was insured for around $100 million.
The Centenary’s whereabouts today is unknown. It was displayed for a number of years at the Tower of London, but whether or not it has been sold since remains a mystery. De Beers has declined to comment, citing its anonymity policy.
If you have any diamonds that you would like to have valued then please contact Simon Rufus at Grand Auctions in Folkestone, Kent for a free auction valuation