Buckingham Palace has confirmed the St Edward’s Crown has been removed from the Tower of London for resizing work.
The work will be carried out by the Crown Jeweller ahead of the Coronation on Saturday, May 6 next year.
The King, along with tradition, will be crowned with the crown during the Coronation Service at Westminster Abbey.
In a statement, Buckingham Palace said on Saturday: "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 May 6, 2023."
The King will also wear the Imperial State Crown during the Service. Further details of Crowns to be worn at the Coronation will be issued in due course.
Versions of the St Edward's Crown are thought to have been used at the moment of coronation for British and English monarchs since the 13th century.
The current crown was made for Charles II in 1661, as a replacement for the medieval crown which had been melted down in 1649.
The original was thought to date back to the 11th-century royal saint, Edward the Confessor, the last Anglo-Saxon king of England.
It is St Edward's Crown that appears in the royal coat of arms of the United Kingdom, the Royal Mail logo and in badges of the Armed Forces.
Charles's coronation is expected to be on a smaller scale and shorter, with suggestions that it could last just one hour.
It is also expected to be more inclusive of multi-faith Britain than past coronations but will be an Anglican service, with the Queen Consort crowned alongside Charles.
Guest numbers will be reduced from 8,000 to around 2,000, with peers expected to wear suits and dresses instead of ceremonial robes, and a number of rituals, such as the presentation of gold ingots, axed.
