It is one of the most famous gems in the Royal Family and has been worn by monarchs and consorts. But this dazzling diamond diadem, although associated with queens, was actually created for a king.

It was made for the coronation of King George IV in 1820, and is known as the King George IV State Diadem. However, the flamboyant king was the last man to wear it. He was succeeded by his brother, King William IV, who spent much of his short reign trying to undo the royal reputation for excess that George had created. William had no intention of donning the diadem. Since then, it has been worn by queen regnants and consorts at coronations and at the State Opening of Parliament.

It should be a familiar sight for royal watchers, as Queen Elizabeth II wore it to the State Opening of Parliament numerous times.

Rundell Bridge & Rundell and Garrard & Company made the tiara of silver, gold, pearls and diamonds. The diadem has a narrow band that is edged with pearls, while diamonds make up the towers. It has four sprays that represent the national emblems of England, Ireland and Scotland (roses, shamrocks and thistles, respectively). In total, 1,333 diamonds decorate the diadem, which includes a four-carat pare yellow diamond that sits in the centre of the front cross. At the time, it cost just £8,216, which was paid for from an account set aside for King George’s coronation.

It is thought that the diadem came from discarded designs for King George IV’s Imperial State Crown by Philippe Liebart.

King George VI wore the diadem to Westminster Abbey ahead of his crowning, and monarchs since have followed in his footsteps. The crown passed from George to his sister-in-law, Queen Adelaide, and was passed down from then to each queen, whether they reigned or were simply consorts.

We are yet to see Queen Camilla wear it but in all likelihood she will and create another chapter in the story of a diamond diadem made for a king but worn by queens.