Queen Victoria officially received Koh-i-Noor diamond in the first week of July 1850!!

Queen Victoria. The Royal Order of Sartorial Splendor

Koh-i-Noor diamond and the British Crown. Odisha Sun Time

Koh-i-Noor diamond's journey. indpaedia.com

 "The British, it is said, acquired their empire in a fit of absent-mindedness. The same cannot be said, however, for the treasures residing in it. When it came to relieving foreign potentates of their valuables – whether by “purchase”, looting or as part of a punitive peace treaty – perfidious Albion was in a league all of its own. So when Britain, or rather its proxy, the East India Company, triumphed over the Sikhs in 1849, it was natural that the resulting Treaty of Lahore should include the transfer of a little booty. And that is why the Koh-i-Noor diamond now sits in a crown in the Jewel House in the Tower of London". ...........Neil

Tweedie 29 Jul 2010; The Telegraph

When it comes to valuable  stuff,  jewelry, gemstones, diamonds, paintings, etc the word "contentment" is anathema to the British royals. Any  valuable spoil of wars in the British colonies is theirs. This is way they seized the most valuable diamond in the world - Koh-i-Noor from the Punjab rulers. 

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Bearman Cartoons

Exactly 218 years ago in the first week of July an important politico-social event took place in London and it was related to the official handing over of one of the  few expensive cut-gemstones in the world  to the British Royalty.  It was on  3 July 1850, the world's most exciting, but mysterious diamond - the Koh-i-Noor was formally presented to Queen Victoria at Buckingham Palace by the deputy chairman of the East India Company. The date had been chosen to coincide with the Company's 250th anniversary. In 1851, the public got a chance to see the most beautiful creation of God and the  exhibition was held in Hyde Park, London. It represented the the pride and political power of growing British Empire's influence in the colonies under their control. No doubt, the diamond's chequered history, mysterious past and its huge value attracted the Britons to the exhibition in large numbers.

Koh-i-Noor diamond  PrimeStyle

Maharajah Ranjit singh, last owner of Koh-i-Noor. Stories of World

Young ruler Duleeo Singh. Portrait by Winterhalter. Pinterest

Koh-i-Noor diamond's journey from India to London is an interesting one. It's last owner Maharajah Ranjit Sigh (1780-1839) willed the diamond to Jagannath Temple, Puri, now in the state of Odhisa; the temple was  under the administration of East India company. After his death in 1839, unfortunately the will was not executed as the English company annexed the kingdom of Punjab. As per the last Treaty of Lahore 9 March 1846 (ratified by Gov. Gen. Marquess of Dalhouse , Koh-i-Noor diamond became Queen Victoria's asset and the assets of the ruler went to the company. As the diamond happened to be a  covetous  spoil of war, Dalhousie wanted the precious stone officially presented as a gift to the Queen Victoria by Duleep Singh, the youngest son of Ranjit Singh.

East India House in c. 1800, painted by Thomas Maltonnen.wikipedia.org

Considering its value and name the rare diamond  was carefully sealed in a small iron safe inside a red dispatch box under tight security arrangements. It was sent  from Bombay  to London on 6 April on board HMS Medea. Surprisingly, the long voyage was itself a difficult one. While anchored at a port in Mauritius, an outbreak of cholera on board threatened the passengers and the port authorities asked the ship to move out quickly. No sooner had they escaped from one ordeal than another one was in the making at sea. The ship, this time, was  hit by a severe gale that did not come down for  12 hours. At last, for safety purpose, the ship reached Spithead, near Portsmouth, on 1 July. Following  morning, Ramsay and Mackeson, in the company of Mr Onslow, the private secretary to the Chairman of the Court of Directors of the British East India Company,  went  to East India House, London and put the diamond into the care of the chairman and deputy chairman of the East India Company. Not happy with the appearance of the diamond (105.602 carats) that had 169 facets Prince Albert wanted the diamond further polished and it was done by the the most famous Dutch diamond merchants, Mozes Costeril. Polishing was done in London and it took almost a month. The newly polished and cut diamond weighed  105.6 carats with 66 facets, including  additional 8 star facets around its cutlet. This work wa done under the direction of Prince Albert. The reduction in sizes is due to the presence of some cleavages that had to be removed. 
http://indpaedia.com/ind/index.php/Kohinoor/_Koh-i-Noor
https://en.wikipedia.org/wiki/Koh-i-Noor