Princess Diana has always been known as a trendsetter.

A new study by Justmylook has revealed that searches for blue eyeliner have spiked by 614 per cent in just one week in the run up to Princess Diana’s 60th birthday. Even though the Princess was one of the most photographed women in the world, many do not know that she had a signature make-up look that was small enough to miss but still had a big impact… Blue eyeliner. Princess Diana used blue eyeliner to amplify the colour of her blue eyes and made them sparkle while giving the face a pop of colour as she typically kept the rest of her make-up very neutral. The eyeliner was also very on-brand for Diana who was known for breaking the mould for Royal style which was typically very toned down. With the Princess’s 60th birthday this week (July 1), and the resurgence of 80’s and 90’s make-up looks it is no wonder demand for her signature look. If you are wanting to try out Princess Diana’s blue eyeliner trick with your own eye colour, you should try choosing an eyeliner colour that is a few shades above or below your eye colour and to avoid an exact match. If you are looking for a dramatic effect, try an eyeliner that is a few shades darker than your eye colour and the opposite to soften your make-up. Beauty experts suggest a deep navy eyeliner for brown eyes, a cobalt eyeliner for green, turquoise for hazel and cobalt for blue. The key to Diana’s application is keeping the eyeliner close to the lash line rather than bringing it up onto the lid. If you are wanting to truly make your eyes pop, try pairing the eyeliner with coloured mascara.