Discovered on 14 February 1972, the Star of Sierra Leone which weighed 968.90 ct. in the rough state is the third-largest rough diamond, and the largest alluvial gem diamond ever found. Harry Winston bought the rough diamond in October 1972, but it was not cut until August 1973. The stone was originally cut into a 143.20ct emerald cut, but upon close examination, it revealed inclusions. The big diamond was re-cut into seven smaller stones, the largest of which weighs 32.52ct. Besides these, the rough was cut into 10 other stones ranging from 1.85ct – 53.96ct. All told, Winston recovered only 238.48ct, a staggering loss of almost 75% of the rough’s weight. 13 of the 17 diamonds, though, are reported to be flawless.
Diamonds of Sierra Leone have an international reputation as one of the highest gem quality diamonds in the world. The diamonds are so pure and free of inclusions, that some of them are known as “glasses”, clear, transparent, and colourless. Even though the diamonds derived from the “Star of Sierra Leone” have not been graded for colour and clarity, in all probability they are D-colour diamonds and perhaps internally flawless.