The Duchess of Cambridge paid a tribute to Princess Diana at Trooping the Colour on Thursday, the first event to kick start the Queen's Platinum Jubilee.
Kate, 40, wore a pair of sapphire and diamond earrings, which used to belong to her late mother-in-law.
Diana was pictured wearing them multiple times over the years, including at the 1996 Met Gala.
On the first day of the jubilee, a long weekend of celebrations to mark the Queen's 70 years as monarch, Kate also wore a white recycled Alexander McQueen blazer dress, complete with a navy and white Philip Treacy hat, with her later wearing a hat from the same designer for Friday's Service of Thanksgiving.
Her hair was swept back into a bun, as she waved in the traditional carriage ride, part of the official royal procession, on her way to the parade ground.
Sitting in the first carriage, she was joined by the Duchess of Cornwall, in blue, and her three children in coordinated outfits, Prince George in a navy suit and pale blue tie, Princess Charlotte in a pale blue dress, and Prince Louis in white sailor-style outfit.
Kate's earrings that stole the show are similar in design to her engagement ring to Prince William, which also previously belonged to Diana.
After her death in 1997, Diana left her own jewellery collection to both her sons. William originally opted for a Cartier Tank watch, while it was Prince Harry who chose the ring.
But, for William's proposal to Kate in 2010, he asked his then single brother if he could use it, to which he agreed, and swapped it for the watch.
William asked Kate for her hand in marriage while on holiday in Kenya. A decade later, delivering a speech during a Buckingham Palace reception marking the UK-Africa Investment Summit in 2020, he recalled the special moment, with his wife in the audience.
"It is the place my father took my brother and me shortly after our mother died. And when deciding where best to propose to Catherine, I could think of no more fitting place than Kenya to get down on one knee."