The Imperial State Crown, which was last seen in public when it was placed on Queen Elizabeth II's coffin for her lying in state and funeral, is a relatively modern artifact.

Made in 1937 for the coronation of King George VI, the Imperial State Crown contains some of the most historic jewels in the royal collection, including the Black Prince’s Ruby, said to have been given to Edward, Prince of Wales (the Black Prince) in 1367. The crown is set with 2,868 diamonds, 17 sapphires, 11 emeralds, and hundreds of pearls. At the center is the Cullinan II diamond, one of the largest in the world.

Once Charles III has been crowned, he will switch the St Edward's Crown for the Imperial Crown for the procession back from Westminster Abbey to Buckingham Palace. Queen Elizabeth II once admitted that she found the headpiece, at 2.3lbs, so heavy that she couldn't look down when reading a speech or her “neck would break and it would fall off” – one of the “disadvantages” to crowns, she confessed.

Coronation Crowns and Other Priceless, Controversial, Royal Treasures