January Jones says the best thing about her 'X-Men: First Class' role is the "ass-kicking white boots" she gets to wear.

The 33-year-old blonde plays telepathic mutant Emma Frost, who has the ability to transform into an 'organic diamond', in the superhero movie, but despite her cool powers January loves her character's wardrobe more.

In an interview in the May issue of W magazine, she said: "As Emma Frost, I'm telepathic, and I can turn into a diamond, which means I'm very, very cold. I always wear white: lots of iridescent stretch leather, lots of sparkle, and ass-kicking white boots."

January is famous for playing Betty Draper in the '60s set advertising drama 'Mad Men'.

But the actress claims her character didn't even feature in the series' pilot episode, and she originally auditioned for the role of Peggy Olson, who is played by Elisabeth Moss.

January revealed: "There was no Betty in the pilot when I auditioned ... I read for Peggy two times - it was between me and Elizabeth Moss who eventually got the part. At the end of the scene, there was a casual mention that Don (lead character Don Draper) was married. Matt (writer Matthew Weiner) went home that night and wrote two scenes that featured Betty. I auditioned a couple of days later, and he made me a verbal promise that the character would grow. I took the part on faith."