The original stone, which weighed in at a whopping 599 carats, was discovered in De Beers's premier mine in 1986. The rough shape of the stone, however, made it difficult to cut and there were even thoughts of cutting it into smaller stones.

In the end, Gabi Towkowsky, one of the world's most accomplished diamond cutters, said it would be made into one large modern-cut stone.

A special room, that took a year to construct, was prepared for the cutting of the diamond. After nearly a year of work, the Centenary, which weighed 273.85 carats and was shaped like a modified heart, was ready.

Two smaller pear shapes were also cut from the same stone.

The Centenary's unique feature is its exceptional clarity; it has been graded as internally flawless. It is said to be the largest, faceted, D-colour, flawless diamond in the world.

While it has never been appraised for its value, the Centenary is known to have been insured for around $100 million at the time of its unveiling in May 1991.

Information courtesy: De Beers Group, Internetstones.com