Royals How Kate Middleton Honors Princess Diana and Queen Elizabeth in Her 40th Birthday Photos The Duchess of Cambridge added the perfect royal accessory to her birthday portraits By Erin Hill Erin Hill Twitter Senior News Editor, PEOPLE People Editorial Guidelines Published on January 8, 2022 05:35 PM Share Tweet Pin Email Kate Middleton on her 40th birthday. Photo: Paolo Roversi Kate Middleton is paying tribute to two of the most iconic royal women in history with her new birthday portraits. The Duchess of Cambridge, who celebrates her 40th birthday on January 9, released three glamorous new portraits in honor of the milestone occasion on Saturday. And Kate made sure to include a subtle nod to both Queen Elizabeth and Princess Diana. In one glamorous photo of Kate in a red satin one-shoulder gown, the royal wears a glittering pair of diamond earrings that belong to the 95-year-old monarch. In a second black-and-white image, Kate is seen in a traditional portrait pose that shows off diamond and pearl drop earrings that belonged to her late mother-in-law Princess Diana. The earrings aren't the only homage to Diana, she also has the royal's iconic sapphire engagement ring in full view. Kate, who has worn both earrings on a few other occasions, regularly channels Princess Diana through her royal style. And she often is seen wearing jewelry from the Queen's collection. Kate Middleton Is Embracing Change Ahead of 40th Birthday: 'She Has Come Into Her Own' Kate Middleton on her 40th birthday. Paolo Roversi The royal mom will celebrate her birthday privately amid the ongoing surge in COVID-19 cases across the U.K. Last year, she celebrated her 39th birthday with a tea party hosted by her husband and their three children, Prince George, Princess Charlotte and Prince Louis, at their country home, Anmer Hall, in Norfolk. Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Kate Middleton on her 40th birthday. Paolo Roversi Kate is preparing more than ever for her role as future queen consort alongside Prince William, taking on more royal duties as Queen Elizabeth has canceled engagements due to recent health issues as well as Prince Harry and Meghan Markle's decision to step back as senior working royals. The Duchess of Cambridge is "flourishing," a royal insider told PEOPLE ahead of Kate's 40th birthday. "She has really come into her own."