The Cullinan Diamond

January 26, 2015

Originally posted 1-24-11

On January 26, 1905 a 3,106-carat diamond was discovered in Pretoria, South Africa. Weighing nearly 1.5 pounds, the Cullinan, as it was named, is the largest diamond ever found. Since the greatest value in such a large diamond is in the number of stones that can be produced, renowned diamond cutter, Joseph Asscher was chosen to cut the diamond. What remained after the stone was finally cut were nine major stones and 100 smaller stones totaling nearly 1,068 carats.

What percent of the diamond’s 3,106-carat total weight was lost as a result of cutting? Express your answer as a percent to the nearest tenth.


The largest of the nine major diamonds cut from the original stone, known as the Cullinan I or the Star of Africa, is now located in the Tower of London, set in the British royal scepter. This stone, with a total weight of 530.2 carats, has an estimated value of 400 million dollars. What is the approximate value of the portion of the diamond lost due to the cutting process, if we assume the same value per carat as the Cullinan I? Express your answer to the nearest dollar.


For his services, Asscher received payment, in diamonds, equivalent to about 1/5 of the total finished weight of 1,068 carats. This is equivalent to what percent of the Cullinan’s original weight before cutting? Express your answer as a percent to the nearest hundredth.