Kate Middleton Wears Princess Diana's Famous Brooch for Royal Engagement with the King

Catherine, Princess of Wales, and Prince William joined the king and queen consort on a major engagement this morning—and Kate made sure to pay tribute to the late Princess Diana.

The four senior royals greeted President of the Republic of South Africa Cyril Ramaphosa in London. To welcome the leader, the family hosted a welcome ceremony on Horse Guards Parade. The president, accompanied by the king, inspected the Guard of Honour after the South African national anthem was played.

His two-day visit marks the first state visit hosted by the United Kingdom with King Charles III as monarch, and the first state visit here by a South African leader since 2010.

For the occasion, Kate was the definition of elegant autumn dressing in a monochrome maroon look. Her sophisticated outfit consisted of a long-sleeved dress with a collared neckline and pleated skirt by Emilia Wickstead. She carried a small Mulberry clutch in the same shade and matching Gianvito Rossi suede heels.

But the accessory that truly took the cake was her pretty Sean Barrett hat, which was embellished with a bow at the back.

For jewelry, Kate wore two special pieces that honor her late mother-in-law, Princess Diana: her diamond-and-pearl drop earrings and her Princess of Wales feather brooch. The beautiful circular brooch contains 18 round-cut diamonds with small emeralds that surround the Prince of Wales feathers symbol. It was given to Princess Diana by the Queen Mother upon her engagement to King Charles III, who was then the Prince of Wales, in 1981.

Diana and Charles separated more than a decade later, in 1992, and divorced in 1996. She passed away in a car accident in 1997.

This article originally appeared in Harper's BAZAAR US.