<P> On 10 February 1908, the rough stone was split in half by Joseph Asscher at his diamond - cutting factory in Amsterdam . At the time, technology had not yet evolved to guarantee the quality of modern standards, and cutting the diamond was difficult and risky . After weeks of planning, an incision 0.5 inches (1.3 cm) deep was made to enable Asscher to cleave the diamond in one blow . Making the incision alone took four days, and a steel knife broke on the first attempt, but a second knife was fitted into the groove and split it clean in two along one of four possible cleavage planes . In all, splitting and cutting the diamond took eight months, with three people working 14 hours per day to complete the task . </P> <P> "The tale is told of Joseph Asscher, the greatest cleaver of the day," wrote Matthew Hart in his book Diamond: A Journey to the Heart of an Obsession (2002), "that when he prepared to cleave the largest diamond ever known...he had a doctor and nurse standing by and when he finally struck the diamond...he fainted dead away". Lord Ian Balfour, in his book Famous Diamonds (2009), dispels the fainting story, suggesting it was more likely Joseph would have celebrated, opening a bottle of champagne . When Joseph's nephew Louis heard the story, he exclaimed "No Asscher would ever faint over any operation on any diamond". </P> <P> Cullinan produced 9 major stones of 1,055.89 carats (211.178 g) in total, and 96 minor brilliants weighing 7.55 carats (1.510 g) (on average, 0.079 carats each)--a yield from the rough stone of 34.25 per cent . There are also 9.5 carats (1.90 g) of unpolished fragments . All but the two largest stones--Cullinans I and II--remained in Amsterdam by arrangement as the fee for Asscher's services, until the South African government bought them (except Cullinan VI, which Edward VII had purchased and given to his wife Queen Alexandra in 1907), and the High Commissioner for Southern Africa presented them to Queen Mary on 28 June 1910 . Mary also inherited Cullinan VI from Alexandra, and she left all of her Cullinan diamonds to her granddaughter Queen Elizabeth II in 1953 . Cullinans I and II are part of the Crown Jewels, which belong to the Queen in right of the Crown . Asscher sold the minor stones to various buyers, including then prime minister of South Africa, Louis Botha, and the diamond merchants Arthur and Alexander Levy, who supervised the cutting of Cullinan . Some were purchased by Mary and set in a long platinum chain, which Elizabeth has never worn in public, saying that "it gets in the soup". </P> <P> In the 1970s, two minor Cullinan diamonds owned by Louis Botha's heirs were analysed by De Beers at their laboratory in Johannesburg, and they were found to be completely free of nitrogen or any other impurities . Cullinans I and II have been examined in the 1980s by gemologists at the Tower of London and both graded as colourless type IIa . </P>

Who has the largest diamond in the world