Close up of the Imperial State Crown set with the second Star of Africa that weighs 317.4 carats. It replaced the Stuart Sapphire that was moved to the back of the crown and its current state was first used at the Coronation of George V and then George VI and Elizabeth II.
Crown of Princess Margaret of York, sister of Edward IV & wife of Charles the Bold, Duke of Burgundy. Made c. 1461. One of 2 English crown that survive from the medieval period. Via Irish Archaeology FB