Royal siblings don't come as glamorous, humble and refreshingly close as Princess Beatrice and her younger sister, Princess Eugenie.
The two daughters of Prince Andrew and Sarah Ferguson share an incredibly close bond, and occasionally go out on their royal duties together.
For Princess Beatrice's 37th birthday, her sister penned the most adorable tribute, alongside a carousel of touching unseen photos.
Taking to Instagram, the 35-year-old wrote: "Happy happy birthday to my dearest Beabea… my big sissy, the best in the entire world."
Princess Eugenie's tribute to her sister
Fans and followers of Princess Eugenie flooded the comment section with birthday wishes and messages of praise, especially for the more everyday, sisterly photos she shared that gave royal fans a bit of a glimpse into their dynamic.
As an eagle-eyed royal style watcher, I couldn't help but notice the final photo, and be particularly caught by the two dresses.
In the snapshot, Eugenie and Beatrice were wearing co-ordinating floral dresses, and looked absolutely magnificent.
The birthday girl was wearing an incredible floral midi dress from the Vampire's Wife, with a cobalt base and gorgeous white and green pattern across it, layered under a navy blue blazer.
Meanwhile, her sister opted for a white halterneck dress from Rebecca Vallence, which featured a blue floral pattern and a cinched waist.
The photo was taken after the opening of the Chelsea Flower Show in May this year, and might just be from a girls' night out that the duo went out on to celebrate the occasion afterwards.
Princess Beatrice's birthday tributes
Princess Eugenie wasn't the only one of her sister's relatives to pen a birthday tribute to her.
Sarah Ferguson also posted a heartwarming video to Instagram, alongside a touching caption, in which she and her daughter shared an embrace.
Alongside the clip, she gushed about her 'incredible bond' with her daughter, expressing how 'endlessly grateful' she is to have her.
Meanwhile, Princess Beatrice's husband, Edoardo Mapelli Mozzi, also paid tribute to his wife on Instagram, posting a beautiful photo of her, and a message on behalf of their immediate family.
He wrote: "Happy birthday to my BEAUTIFUL wife. You are the greatest. We love you so much. E,W,S,A xxxx [heart emoji]".