Francisco Costa only wants to work with ''feminine and cool'' stars.

The Calvin Klein creative director has dressed a string of diverse high profile women, including Rihanna, Jennifer Lawrence and Rooney Mara and says he loves ''natural'' women.

He said: ''They're all really strong, independent people. They have a point of view. They're feminine and cool. You know, they're natural.

''The person has to have a certain level of confidence. We keep our red carpet dresses simple - but always glamorous.''

For Francesco, key to his designs is being timeless.

He said: ''I don't want anything that can date you or that feels like you've been put in a time capsule. Calvin always looked forward, never back.''

And the designer thinks it is important to work with high-profile stars, both in dressing them for the red carpet and getting them to his shows.

He told Grazia magazine: ''I love it for many reasons. It brings a lot of awareness to the brand, so I think it's very important. We do it deliberately.''