Valentino's partner, Giancarlo Giammetti, has posted a picture on Instagram of an effortlessly elegant Princess Diana looking stunning in a bikini on the designer's yacht.
Giancarlo posted the 'Throwback Thursday' picture along with the caption: "Summer is here TBT princess Diana on the TMblue 1990 #princessdiana."
The picture sees Diana on Valentino's TM Blue One yacht along with Rosario Saxe-Coburg, wife to the Prince of Preslav, Bulgaria.
According to the Daily Mail, Mr Giammetti was actually with the princess on her boyfriend Dodi Al Fayed's Jonikal yacht just hours before her fatal car crash seven years later. Dodi's yacht had been anchored next to the TM Blue One.
Princess Diana was a style icon for her generation, and her fashion even influences her daughter-in-law, Duchess of Cambridge, Kate Middleton, today.
For her royal tour of New Zealand and Australia, Kate stepped off the plane in NZ wearing a Catherine Walker coat and a pillbox hat once owned by Diana.
And, of course, Duchess Kate wears Diana's stunning sapphire engagement ring from her marriage to Prince Charles.
MORE PRINCESS DIANA! The 'people's princess', Diana was not only warm and caring , but she was also a fashion leader. See more pictures of her style in our gallery below:
WATCH! Naomi Watts talks taking on the role of a lifetime, playing Princess Diana: