Kate, 37, wore the sash of the Royal Victorian Order over her shoulder, the first time she has worn the honour after it was gifted to her by the Queen for her and Prince William's eighth wedding anniversary in April, People Magazine reports.
It was a night of white with Her Majesty the Queen, First Lady Melania Tump and Camilla, Duchess of Cornwall all opting for floor length ivory gowns.
Queen Elizabeth wore her ancestor Queen Victoria's Crown Ruby earrings and marching necklace, as well as a stunning diamond tiara encrusted with large rubies.
The monarch designed the jaw dropping jewellery herself with 96 rubies which were gifted to her from the people of Burma in 1973, according to Express.co.uk.
Also in attendance were Prince Andrew, Anne, Princess Royal, Prince Edward and his wife Sophie, Countess of Wessex as well as British Prime Minister Theresa May and Mr Trump's four adult children, Ivanka, Tiffany, Eric and Donald Jr.