The duchess also donned the Dame Grand Cross of the Royal Victorian Order on a blue sash, after being given the honour by Queen Elizabeth II back in April in recognition of her services to the sovereign.
Also in attendance at the event was the Duchess of Cornwall who looked equally as resplendent in an ivory A-line gown which featured subtle embroidery across the skirt and up the sleevs. The tiara was originally made by jeweller Garrard by request of Queen Mary in the early 1900s.
The Diplomatic Corps reception witnessed over 1,000 guests attend it. Ambassadors, high commissioners and government officials were among the attendees of the white-collar event. The royal mom of three dusted off her favorite pearl and diamond tiara for the "white-tie" occasion wearing the Cambridge Lover's Knot for the fifth consecutive year. It is not known whether Kate borrowed the ring from the Queen's large jewellery collection, or whether it is a new acquisition - possibly a gift from husband Prince William. It has been seen on Kate just once before, in 2014, at the National Portrait Gallery in London.
The Duchess of Cornwall opted for a cream embroidered gown by Bruce Oldfield, a diamond Boucheron tiara and pearl choker and pearl earrings on Wednesday. The Queen wore a diamond and emerald necklace to match.
© WPA Pool - Getty Images At a Buckingham Palace banquet for a USA state visit in June 2019.
Meanwhile Her Majesty the Queen was dressed in a white floor-length gown adorned with lace, with a matching pair of white evening gloves.
The Diplomatic Reception is the largest event held inside Buckingham Palace with 1000 people invited from more than 130 countries.