Nicole Richie has dyed her hair grey.

The 31-year-old fashion designer showed off her newly-silver tresses at the Met Ball at New York's Metropolitan Museum of Art last night (06.05.13), sticking to the Costume Institute Gala's 'Punk: Chaos to Couture' theme by matching her updo and white Topshop column dress with a red and gold manicure, multiple gold earrings and a dark burgundy lip.

Nicole - who has five-year-old Harlow and three-year-old Sparrow with husband Joel Madden - had earlier teased fans about her change of look, posting pictures of hair extensions lying on a bush and a bowl of dye onto her Instagram account.

Alongside the pictures, she wrote: ''Even the bushes have extensions! Happy Met Ball Monday!

''Hair Time #MetBall (sic)''

And the 'Fashion Star' host wasn't the only star to change their hair for the annual fashion extravaganza.

Anne Hathaway - who shaved her head for her role in 'Les Miserables' - showed off a short blonde crop, which she admitted she wanted to keep forever, though she knows she'll have to revert back to her famous dark tresses soon.

Anne - who wore black vintage Valentino - said: ''It's temporary. But as soon as I did it, I thought I didn't want it to be temporary any longer. I know I have to dye it back for my work.''

And Kerry Washington teamed her low-cut purple, black and blue Vera Wang gown with long leather gloves and purple streaks in her hair.

She said: ''In honour of Vera's design I put all these purple highlights in my hair to have a punk moment. I've never done anything like this before in my life!''