The Duchess of Cornwall has worn her first royal tiara, loaned by the Queen, for her inaugural royal banquet.
Camilla's lace evening dress was made by Robinson Valentine
The diamond headpiece, made in 1911, was the Durbar Tiara previously worn by Queen Mary in Delhi to celebrate King George V's coronation.
The Buckingham Palace banquet was in honour of the king and queen of Norway, who are on a UK visit to mark 100 years of Norwegian independence from Sweden.
King Harald V was seated between Camilla and her mother-in-law.
Camilla, who was accompanied by Prince Charles, wore a lace midnight evening dress for Tuesday's banquet in the palace's Ball Room.
The dress was by her favourite designers Robinson Valentine, the makers of her wedding outfit.
Her tiara, a circle of brilliant-cut diamonds arranged as forget-me-nots and lyres, was made by Garrads in 1911 for Queen Mary.
It was last worn in public by the Queen Mother in 1947 when Queen Mary lent it to her for an official tour to South Africa.
It became part of the Queen Mother's private jewellery collection which was passed to her daughter after her death.
It is believed the Queen has never worn the priceless piece of jewellery.
Norway's Crown Princess is due to give birth in November
King Harald and Queen Sonja had earlier been greeted by the Queen and the Duke of Edinburgh at Buckingham Palace, where they are staying.
The Norwegian royals had arrived in London for their three-day visit on their private yacht.
At Buckingham Palace, the duke and king inspected a guard of honour, and then a gun salute was fired from nearby Green Park.
Crown Prince Haakon and his heavily pregnant wife, Crown Princess Mette-Marit, accompanied the regents.
After lunch at the palace, they viewed a special exhibition of Norwegian items from the Royal Collection.
The royals also met the prime minister and his wife at Downing Street.