How Kate Middleton Paid Tribute to Princess Diana in Her 40th Birthday Portraits

Kate Middleton turns 40 today, and to celebrate the milestone birthday, the Palace released a series of stunning new portraits of the royal.

In the photos, taken by Italian fashion photographer Paolo Roversi, Kate modeled three Alexander McQueen looks (a go-to designer for the royal), and paired each one with accessories that subtly paid tribute to both Princess Diana and Queen Elizabeth. For the first snapshot, the Duchess of Cambridge is dressed in an ethereal white tulle gown with an off-the-shoulder neckline. She wore pearl earrings that once belonged to Diana and her sapphire engagement ring is in full view. A second image shows her in a gorgeous one-shoulder dress in a vibrant shade of red. This time, she's smiling directly into the camera and her glittering diamond earrings are on loan from the Queen's collection of jewelry.

Meanwhile, the third, is more of a headshot with Kate wearing another white ruffled gown. Her hair is styled in relaxed waves that are tousled to the side.

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The photographs were taken in November at London's Royal Botanic Gardens, and will enter the permanent collection of Britain's National Portrait Gallery.

As for how she'll be celebrating the day, Kate will have a "modest" celebration surrounded by loved ones, according to a Palace source at Closer Weekly. "She'll be spending it with the people she loves most – her family," the insider said, adding that her husband Prince William has "arranged a romantic out-of-town getaway in January, for just the two of them."