Princess Diana loved to play up her striking blue eyes with makeup and for the longest time was hardly ever seen without her signature blue eyeliner. But it soon gave way to a different set of hues, and now, her longtime makeup artist is revealing why.

LONDON, UNITED KINGDOM - JANUARY 01: Diana, Princess of Wales, attends a State Banquet at Parliament Building during her official visit to Hungary on May 8, 1990 in Budapest, Hungary.The princess wears a Catherine Walker strapless dress. (Photo by Georges De Keerle/Getty Images)

In a new interview with Yahoo, Mary Greenwell revealed why she convinced the princess to ditch the blue eyeliner, saying, 鈥淚 think beiges and browns are just so much prettier. Simple as that.鈥

While the princess took more risks with her fashion choices, Diana stayed within her own comfort zone when it came to her beauty look. 鈥淪he felt no need to be showy, so she kept her makeup subtle and appropriate for the occasion,鈥 Greenwell explains. 鈥淪he loved to exaggerate her gorgeous eyes and wear loads of mascara.鈥

Of course, her royal position is part of the reason why the Princes William and Harry鈥檚 mother wasn鈥檛 able to go crazy with her makeup. Greenwell says, 鈥淪he was someone who was in the public eye presenting herself all the time to the public. It isn鈥檛 particularly appropriate to go on changing your look every five seconds. She did change her makeup a bit. It鈥檚 just that it wasn鈥檛 changed dramatically.鈥

The late princess and pro approached those subtle differences in products and shades with a purpose in mind. 鈥淪he loved makeup and loved experimenting. It wasn鈥檛 to the point of going from green eyeshadow to blue eyeshadow, but just experimenting with ways to bring her eyes out more,鈥 Greenwell says. 鈥淚t was just much more about really getting her to look absolutely beautiful all the time.鈥

Do you think Princess Diana looked gorgeous in any shade of eyeliner? Let us know @BritandCo!

(Photo via Hulton Archive/Getty, Newsmakers/Getty)