Royals Queen Elizabeth Snuck in a Romantic Nod to Prince Philip in His 99th Birthday Portrait The Queen wore a sweet symbol of love for her husband's milestone birthday By Erin Hill Erin Hill Twitter Senior News Editor, PEOPLE People Editorial Guidelines Published on June 11, 2020 02:24 PM Share Tweet Pin Email Trending Videos Queen Elizabeth and Prince Philip at Windsor Castle. Photo: Steve Parsons/PA Queen Elizabeth is wearing her heart on her sleeve! The famously reserved monarch, 94, included a rare and romantic nod to husband Prince Philip in their joint portrait in honor of the Duke of Edinburgh’s 99th birthday. The Queen wore a heart-shaped brooch to celebrate her husband’s milestone. The sparkling Cullinan V diamond brooch features an 18.8 carat heart-shaped diamond that was cut from the largest diamond ever found, the 3,106 carat Cullinan. The beloved accessory belonged to the monarch’s grandmother, Queen Mary. The brooch is a sweet symbol of love and a fitting choice for the Queen to wear in honor of her husband’s birthday. How Queen Elizabeth Is Keeping Calm & Carrying On at 94: 'She Has Impeccable Judgment' Queen Elizabeth and Prince Philip. Antony Jones/Getty Despite their closeness, the royal couple won’t ever be seen holding hands in public due to the “stoic values” of their generation, according to royal biographer Gyles Brandreth. The Queen and Philip, who has said that the secret to their 72-year marriage is the fact that he makes her laugh, rang in the royal’s 99th birthday on Wednesday with a low-key lunch at Windsor Castle, where they have been in isolation since March. 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! The royal family has been staying in touch via FaceTime — just like families all over the world. “We’ve been talking to all the family online. And it’s been a really good way of keeping in touch and seeing each other,” Prince William said.