The Imperial State Crown, seen lying on top of Queen Elizabeth II's coffin, will be removed in a ceremony on Monday at Windsor, breaking the late monarch’s link with the position she has held for 70 years.
The crown, which includes 3,000 stones and is estimated to be worth between £3 billion ($3.42bn) and £5bn, dates back to the reign of Queen Victoria.
It was placed on top of the queen’s coffin while she was lying in state in Westminster Hall, and it remained in place during the state funeral on Monday.
It will be removed along with the Orb and the Sceptre by the Crown jeweller in a ceremony at St George's Chapel in Windsor prior to the final hymn.
The objects will be passed with the help of the bargemaster and sergeants-at-arms to the dean, who will place them on the altar.
At the end of the final hymn, King Charles III will place the Queen's Company Camp Colour of the grenadier guards — a regimental flag that is specific to the queen — on the coffin.
The lord chamberlain will then “break” his wand of office and place it on the coffin to create a symmetry with the three instruments of state that have been removed.
It will then be returned to the Tower of London, where it is kept under guard as the centrepiece of the Crown Jewels exhibit.
The crown was made in 1937 for the coronation of her father, King George VI, and the history of monarchs wearing an Imperial State Crown dates back more than 700 years.
It includes the Cullinan II stone, which was cut from the largest diamond ever recorded — a 3,601-carat rock discovered in Africa in 1905. It was given to Edward VII by Transvaal, now South Africa, in 1907 for his birthday.
The crown, which is the most important item in the coronation, was shortened an inch for the queen, and she wore it most years during her reign for the State Opening of Parliament.
She once spoke about how heavy it felt on her head.
“Fortunately my father and I had about the same shape of head and once you put it on, it just stays. It just remains itself,” she told the BBC.
“And you can’t look down to read the speech. You have to take the speech up, because if you did your neck would break.
“So there are some disadvantages to crowns, but otherwise they are quite important things.”
Historian and author of The Crown Jewels, Anna Keay, told the BBC it can be quite hard to look at the piece.
“It's literally dazzling … visually overpowering,” she said.