The brooch, made of platinum, was completed in 1953, the year that Princess Elizabeth was crowned Queen Elizabeth II.

The brooch quickly became a favourite in the new Queen’s jewellery box; it was front and centre in a series of portraits, also featuring Prince Charles and Princess Anne, that was taken by Marcus Adams in late 1954.

The size of the brooch, and the prominence of the famous pink diamond, made the piece especially well-suited for important diplomatic occasions. 

Speaking about the brooch, Max Stone said: “This diamond is one of the rarest flawless pink diamonds in the world.” 

He estimates its value to be around £25million, making it the second most expensive brooch in Her Majesty’s brooch collection.

The Queen has worn the brooch for notable royal occasions over the years, including the 1981 wedding of Prince Charles and Princess Diana, as well as the wedding of Prince Edward and Sophie, the Duchess of Wessex in 1999.

More recently, Elizabeth wore the brooch to the Royal Ascot in 2011 and to the Elysée Palace during an official visit to Paris in 2014.