Why Hollywood's most iconic blondes are going brunette (and the five secrets to getting it 'just right')

It started with Cate Blanchett at the Baftas. Then came Emilia, Emma, and Charlize. All iconic Hollywood blondes. All now brunette. So what's the story? As a blonde, I wanted to know. Is my time up? Should I jump ship? Is there some new reason why these perennial blondes are taking their hair colour in the opposite direction?

Not one to follow trends, on this occasion I am intrigued. Not least because on all four of these women, the switch to dark, rich brown looks so ageless; So shiny, so chic, so elegant. And yet, it's such a departure from the icy tones that have become a signature part of their characters on and off screen.

Especially in Blanchett's case, who, until now, has never gone brunette. Think of Blanchett, and you think of her milky skin tone that blends seamlessly into her creamy hair; calm, cool and collected, she, like Theron, is a prime example of how blonde has come to represent her personality.

'With Cate, she chose to go brunette for her role in her London play, but it was a decision that we debated for a while before taking the plunge,' explains Blanchett's hair colourist, Nicola Clarke who also flew to LA to take Emilia Clarke brunette ahead of Oscars.

'With Emlia, she did it for herself. Having wrapped the last season of Game of Thrones, it marked the end of the  chapter. She wanted a new start and the Oscars presented the perfect opportunity to debut a new look,' says Clarke.

But, if you've only known blonde, how do you know if brunette will suit you? 'If you have blue or green eyes, a darker hair shade will set off the colour. Cate has blue yes, and Emilia green, therefore I knew going brunette would make an impact on them. Plus, dark hair reflects the light, so it naturally gives off more shine than blonde hair which absorbs light,' she explains.

Yet, Clarke warns going from blonde to dark is not so easy to reverse so it's vital that you take your time to consider a big colour change. 'Don't do it on a whim. Discuss the idea with your colourist then sit with it for a week or so. It's not just your hair that will change, it will alter how you dress, how you do your makeup.

You'll feel and move differently - hair colour has more of an impact than you think, so it's worth considering all of these points first, then you can take the plunge with confidence,' encourages Clarke.

Ready to move to the dark side? These are celebrity colourist Nicola Clarke's top five secrets to becoming an ageless brunette

1. Go for more than one one shade

'A single shade of brown can look flat and dull your skin tone. When going from blonde to brunette, I recommend adding low lights to the hair first, then painting a brown tint in between the foils to give a three dimensional look to your colour. This is what I did with Emilia and Cate, which set their skin alight.'

2. Colour the ends last

'I always colour the ends of hair for ten or fifteen minutes at the last minute. This is key when going from blonde to brown as the ends are more porous than the roots, so unless you tint them last, they will grab onto the tint and look darker than the rest of your hair.'

3. Consider a makeup and fashion update

Take a note from Charlize Theron at the Oscars and try a bolder colour on your lips. 'When you undergo such a dramatic hair colour change, you'll need to update your wardrobe from your clothes to your makeup. It only needs to be a few key updates, but a brighter lip colour or a couple of statement pieces in your wardrobe will make your skin and hair pop.'

4. The cut is just as important as the colour

'Brunette is  bolder than blonde, therefore a sharper cut than what your used to will give you an air of gravitas. Beachy tousled waves won't look as modern as a graphic bob. Plus, if you've gone from blonde to brunette, trimming off your formally bleached ends will make your hair look and feel more youthful and healthy.

5. The right products are everything when it comes to glossiness

'It's worth remembering that actresses on the red carpet have a personal hair stylist to blow dry their hair with professional products to make it look ultra shiny. If you want your hair to look glossy and healthy you'll need to invest in repairing and conditioning products to maintain a ageless look.' Nicola recommends Virtue, a smart bio-tech brand that utilizes keratin for strong, healthy hair, preventing breakages commonly associated with chemical colouring.

Charlize Theron as the blonde we've always known her as.

Stunning, classic and surprisingly flattering, Charlize wears brunette well.

Emma Stone as a bubbly blonde.

And with deep brown hair that sets off her eyes at the Oscars.

The ice queen herself, Cate Blanchett as the quintessential cool blonde, and now as a glossy brunette.

Nicola Clarke is available at her salon Nicola Clarke at John Frieda