Diamonds of Sierra Leone
Famous Diamonds of Sierra Leone
Two of the world’s ten largest and most famous rough diamonds were discovered in the gravels of the Woyie River flowing through the town of Koidu. Tributaries of the Woyie River have drained the areas surrounding the Koidu kimberlite pipes and dykes over millions of years, concentrating diamonds and other heavy minerals derived from the kimberlite into rich alluvial diamond deposits.
The first large diamond to be recovered from the Woyie River in March 1943 weighed 249.25 carats, followed by an even larger 532 carat stone in June of the same year. The Woyie River Diamond, weighing 770 carats, was found in January 1945 and, at that time, was the largest alluvial diamond known. After a hiatus of almost 27 years, the fourth and largest diamond to be recovered from the Woyie River presented itself on the picking table of the Diminco recovery plant. The Star of Sierra Leone, as it became known, weighed 968.9 carats and is currently ranked the third largest rough diamond in the world, with the Woyie River Diamond in sixth place.
Although being of the finest colour, both the Star of Sierra Leone and the Woyie River Diamond contained flaws and impurities which dictated the number and shape of the polished stones finally separated from the original rough diamond. The Star of Sierra Leone was first cut into an emerald shaped stone weighing 143.2 carats but was later re-cut due to an internal flaw into seventeen smaller stones. Six of the stones, including the largest which weighed 53.96 carats, were incorporated into the Star of Sierra Leone Brooch. The Woyie River Diamond was cut into 30 gem stones, the largest of which was an emerald cut weighing 31.35 carats and became known as the Victory diamond.