Keira Knightley paints her nails in crazy colours for fun.

The 29-year-old actress admits her strangest beauty ritual is swapping the French manicure she usually sports when she's on a film job for completely ''absurd'' shades as soon as she has time off.

She said in an interview with Britain's HELLO! magazine: ''During filming I am carefully made-up for weeks, so at the end of every film I love to go out and buy nail polish in the most absurd colours and paint my nails with them.

''Last time I chose yellow - which I don't recommend. I looked like I and nicotine-stained fingers. I won't repeat the yellow experience, but you can count on me to find an even crazier shade next time.''

Keira, who is married to The Klaxons musician James Righton, stars in a glamorous new campaign for Chanel's Coco Mademoiselle fragrance and says the classic brand was responsible for converting her to women's fragrances.

The 'Jack Ryan: Shadow Recruit' actress revealed: ''My grandmother wore Chanel No. 5 and a friend once gave me a bottle of Coco Mademoiselle. Until then, I had never worn women's fragrances because I found them too sweet or floral.

''Suddenly, people were stopping me in the street to ask what perfume I was wearing. I was really proud.''

Keira also shared her top three beauty picks for looking her best at all times.

She added: ''A cream for dry skin from Australia, a moisturising lotion and a Chanel eye pencil.''