Happy 40th birthday, Kate Middleton! The Duchess of Cambridge has reached a birthday milestone, and while she is reportedly keeping a low profile in the actual celebration, many are eager to pay tribute to the future Queen of England. In a gorgeous example of a tribute to Kate, the National Portrait Gallery, of which Kate is a longtime patron, has released three beautiful new images of the Duchess, which the Cambridges shared on their Instagram page.

The first image, shared by the couple on Saturday evening ahead of the event, shows Kate in a nostalgic black and white, ethereal white dress with pearl earrings. The choice of jewelry was actually with Princess Diana in mind: the Collingwood pearl and diamond drops belonged to the late Princess Diana, which makes it all the more significant that the jewelry stands out in the portrait.

The second portrait shared by the royal family shows Kate smiling in a one-shoulder red dress by Alexander McQueen (she wears the designer's dress in all three images). The portrait, which was released on the morning of her birthday, also notes that it will be on display at the National Portrait Gallery. The photographs, taken by Paolo Roversi at Kew Gardens, will be part of the gallery's "Coming Home" exhibition. Each photograph will be displayed in a different location - Berkshire, St. Andrews, and Anglesey - and will become part of the gallery's permanent collection.

The third image is a black-and-white photograph of Kate in a white dress, which gives her the swagger of a 1980s prom queen. This image is accompanied by a note from Kate herself." Thank you to everyone who wished me a happy birthday and to Paolo and the National Portrait Gallery for these three special portraits." She signed the note with a "C" meaning Catherine.

According to the Daily Mail, palace officials also explained that the image shows three aspects of Kate's personality. The source said, "There's the dignified side to her, as you can see in the classic shot of her staring off into the distance, the more casual image of her as a 40-year-old modern woman in a red dress, and the close-up that offers a more intimate perspective."

Happy birthday, Kate!