The St Edward's Crown has been removed from the Tower of London in preparation for King Charles' coronation.
The 74-year-old royal took the throne in September following the death of his mother, Queen Elizabeth, but will formally be crowned in an official ceremony in May next year, and ahead of the occasion, the Crown Jewels centrepiece has been taken away for modification work.
Buckingham Palace said in a statement: "St Edward's Crown, the historic centrepiece of the Crown Jewels, has been removed from the Tower of London to allow for modification work to begin ahead of the Coronation on Saturday May 6 2023."
Versions of the crown are thought to have been used at the moment of coronation for British and English rulers since the 13th century, with the current one made for Charles II in 1661 as a replacement for the medieval version, which was melted down in 1649.
It is believed the original dated back to Edward the Confessor, the 11th century royal saint who was the last Anglo-Saxon king of England.
Charles' coronation will take place at Westminster Abbey and his son Prince William - who received the title Prince of Wales after his father took the throne - is believed to be taking an "active role" in helping to plan the ceremony and ensure it reflects modern Britain.
According to reports, experts have recommended that "archaic" and "imperial" elements should be dropped from the ceremony when Charles is crowned.
Queen Consort Camilla will also be crowned at the event but is not believed to be taking an active role in the planning and it is not yet clear if the Duke of Sussex will be involved as he is no longer a working royal.
It is believed the "royal-wedding sized" with around 2,000 guests - far less than the 8,000 who attended the coronation of the late Queen Elizabeth in 1953.
Dr. Bob Harris, of The Constitution Unit at University College London, wrote: "The UK no longer has the capacity to mount anything like this spectacle, nor should it do in straitened times.
"The next coronation will inevitably be smaller. Archaic elements such as the Court of Claims should be dropped.
"So should the homage, and thought be given to how the King as head of the nation should be enabled early in the reign to signify support for, and encouragement of, modern civil society.
"A modernised form of homage could take place, for example, in Westminster Hall, on in a procession on Horse Guards parade."
A spokesman for Buckingham Palace has previously said about the ceremony: "The coronation will reflect the monarch's role today and look towards the future, while being rooted in long-standing traditions and pageantry."