As for the Cullinan V, that was included in the crown when Queen Mary wore the piece again, this time as a regal circlet, for the 1937 coronation of her son and Elizabeth's father, King George VI.

Queen Adelaide's ornate crown from 1831 is one contender. Wearing a white and gold dress, King William IV's wife commissioned a brand new coronation crown for their coronation. Rather than use ...

Queen Mary wearing her coronation regalia (L) including the crown, coronation ring and two scepters, 1911. And Queen Elizabeth The Queen Mother photographed as she was crowned at Westminster Abbey ...