St Edward's Crown is one of the oldest Crown Jewels of the United Kingdom and the centrepiece of the coronation regalia. Named after Edward the Confessor, it has traditionally been used to crown English and British monarchs at their coronation ceremonies. The current version was made for the coronation of Charles II in 1661.

Although it is regarded as the official coronation crown, only six monarchs have been crowned with St Edward's Crown since the Restoration: Charles II (1661), James II (1685), William III (1689), George V (1911), George VI (1937) and Elizabeth II (1953).

Mary II and Anne were crowned with small diamond crowns of their own; George I, George II, George III and William IV with the State Crown of George I; George IV with a large new diamond crown made specially for the occasion; and Queen Victoria and Edward VII chose not to use St Edward's Crown because of its weight and instead used the lighter 1838 version of the Imperial State Crown. When not used to crown the monarch, St Edward's Crown was placed on the altar during the coronation; however, it did not feature at all at the coronation of Queen Victoria.

Before 1649, it was usual for a monarch to be crowned with the original St Edward's Crown, and often to have several crowns placed on his or her head during the ceremony.

More Info: en.wikipedia.org