The priceless piece, which is more than 150 years old, was the perfect accessory to match her bottle green Bruce Oldfield dress for the reception at Buckingham Palace. Below the diamond-studded coronet is a banner bearing the words Ich Dien (I serve).
It was fashioned into a necklace by the late Princess of Wales, who wore it to a glittering gala evening in 1986 with a pair of matching emerald earrings.
Diana was on a state visit to Austria with Charles when she wore the dazzling jewel to the Burgtheater in Vienna.
It was first given as a wedding gift to Princess Alexandra of Denmark in 1863 by the Ladies of Bristol when she married Bertie, Prince of Wales (later King Edward VII and Queen Alexandra).
Following Alexandra’s death, the brooch was reportedly handed down to her daughter-in-law Queen Mary and then onto the Queen Mother, who subsequently passed it on to Diana on her marriage to Charles in 1981.
