Source: George III & Queen Charlotte; Patronage Collecting and Court Taste, Edited by Jane Roberts, Essays by Christopher Lloyd and Jonathan Marsden, Royal Collection Publications, 2004
In 1767 the Nabob of Arcot “presented George III and Queen Charlotte with a gift of arms and jewels which included seven large diamonds, subsequently known as the Arcot diamonds. In her will Queen Charlotte specifically directed that they were to be sold and the money divided among her four younget surviving daughters. George IV disregarded his mother’s will and claimed the diamonds as his own personal property, apparently setting them into the new Imperial State Crown in 1821. After the coronation of William IV and Queen Adelaide in 1831 - when the diamonds were set in the Queen’s crown - the diamonds were sold to Rundells, who auctioned them at Willis’s Rooms, St James’s, on 20 July 1837. There they were purchased by the Emanuel Brothers, who sold them to the 1st Marquess of Westminster for £11,000. In 1930 the two largest stones were set in the Westminster tiara, .....”
EDITED much later Queen Victoria acceded to the throne on 20 June 1837