Her sapphire and diamond jewellery perfectly complimented her blue bespoke Emilia Wickstead dress, which she wore to meet the President of Ukraine, Volodymyr Zelenskyy, and his wife, First Lady Оlena.
Kate Middleton paired her Emilia Wickstead dress with sapphire and diamond jewellery
On closer inspection, several royal fans have been left wondering whether her jewellery was from William's late mother Princess Diana – like her coordinating engagement ring.
The Duchess has been pictured wearing drop sapphire earrings in the past, which were originally a wedding gift to Diana – part of a suite of jewels given by Crown Prince Fahd of Saudi Arabia. Kate updated the design into a drop style after Prince William gave the earrings to his then-fiancee in 2010.
WATCH: Kate Middleton's stunning jewellery collection will leave you speechless
The royal's new necklace followed the same design, with one small sapphire surrounded by diamonds, connected to another larger pendant below. Since it bears similarities to another pair of earrings from Diana's collection, some Twitter users have been speculating that she may have turned the original design into a new necklace.
Next to a photo comparing the necklace and earrings, Kate's Closet posted: "A closer look at Kate's new sapphire and diamond pendant necklace. @allthingsroyal suggests the stones may originate from Princess Diana's Saudi sapphire suite. It seems the drop earrings from the parure were used to create the pendant."
Princess Diana had a stunning collection of jewellery
All Things Royal noted in the comments section: "The pendant with the bigger sapphire on the pendant is why I think it might be from the Saudi suite. And it doesn't have to be an earring from that suite. Every jewel in that suit was very versatile."
While Kensington Palace has not confirmed whether Kate's necklace is, in fact, a new addition to her jewellery box, or if fans have correctly identified an item from Princess Diana's personal collection, her outfit of choice earnt her plenty of compliments.