This famous sapphire is set at the top of the British Imperial Crown which also features the Cullinan II Diamond, the Black Prince’s Ruby, and the Stuart Sapphire.
St. Edward’s Sapphire from the top of the Imperial State Crown. The four large drop-shaped pearls are said to have been the earrings of Elizabeth I
Even older than that is St. Edward’s Sapphire, originally set in the Coronation Ring of Edward the Confessor at his crowning in 1042. It remained with him in Westminister Abbey until 1101 when the ring was broken up and this and the other jewels removed.
The reverse of The Imperial State Crown shows the St Edward’s Sapphire set in the cross on top of the crown, and the large Stuart Sapphire near the headband.