In 1907, the Transvaal Colony government bought the Cullinan and Prime Minister Louis Botha presented it to Edward VII.

The second-largest is Cullinan II or the Second Star of Africa, weighing 317.4 carats (63.48 g), mounted in the Imperial State Crown.

Seven other major diamonds, weighing a total of 208.29 carats (41.66 g), were privately owned by Elizabeth II, who inherited them from her grandmother, Queen Mary, in 1953.

The Cullinan is estimated to have formed in Earth's mantle transition zone at a depth of 410–660 km (255–410 miles) and reached the surface 1.18 billion years ago.

In April 1905, the rough gem was deposited with Premier Mining Co.'s London sales agent, S. Neumann & Co.[7] Due to its immense value, detectives were assigned to a steamboat that was rumoured to be carrying the stone, and a parcel was ceremoniously locked in the captain's safe and guarded on the entire journey.

Initially, Henry Campbell-Bannerman, then British Prime Minister, advised the king to decline the offer, but he later decided to let Edward VII choose whether or not to accept the gift.

[16] The king asked his colonial secretary, Lord Elgin, to announce that he accepted the gift "for myself and my successors" and that he would ensure "this great and unique diamond be kept and preserved among the historic jewels which form the heirlooms of the Crown".

[17] The king chose Joseph Asscher & Co. of Amsterdam to cleave and polish the rough stone into brilliant gems of various cuts and sizes.

[13] Meanwhile, to much fanfare, a Royal Navy ship carried an empty box across the North Sea, again throwing off potential thieves.

After weeks of planning, an incision 0.5 inches (13 mm) deep was made to enable Asscher to cleave the diamond in one blow.

[22] 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.

[25] All but the two largest stones – Cullinans I and II – remained in Amsterdam by arrangement as the fee for Asscher's services,[26] 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.

[28] Asscher sold the minor stones to the South African government, which distributed them to Queen Mary; Louis Botha, the then prime minister of South Africa; the diamond merchants Arthur and Alexander Levy, who supervised the cutting of Cullinan;[29] and Jacob Romijn (later Romyn), who co-founded the first trade union in the diamond industry.

[31] In the 1960s, two minor Cullinan diamonds owned by Louis Botha's heirs were analysed at the De Beers laboratory in Johannesburg and found to be completely free of nitrogen or any other impurities.

[40] Cullinan II, or the Second Star of Africa, is a cushion-cut brilliant with 66 facets weighing 317.4 carats (63.48 g) set in the front of the Imperial State Crown,[34] below the Black Prince's Ruby (a large red spinel).

On 25 March 1958, while she and Prince Philip were on a state visit to the Netherlands, Queen Elizabeth II revealed that Cullinan III and IV are known in her family as "Granny's Chips".

[47] Cullinan V is an 18.8-carat (3.76 g) heart-shaped diamond set in the centre of a platinum brooch that formed a part of the stomacher made for Queen Mary to wear at the Delhi Durbar in 1911.

[34] It hangs from the brooch containing Cullinan VIII and forming part of the stomacher of the Delhi Durbar parure.

After his death she gave the jewel to Queen Mary, who had it set as a pendant hanging from the diamond-and-emerald Delhi Durbar necklace, part of the parure.