Left: In Iron Man 2. Right: Photo: Jesse Grant/Getty Images

Scarlett Johansson looks great as a blonde. She also makes a totally convincing brunette. And, come to think of it, she pulls off red hair pretty well, too. Scarlett seems to be one of those rare women with chameleon-like coloring that allows her to look great in virtually every hair hue she adopts. Intrigued by this concept, I asked Regis Artistic Director, Kat Carey, why some people can wear pretty much any hair color they want, while others seem to have to stick with what they were born with. Here’s her take:

One of the key factors in being able to transform your hair color is skin tone. It doesn’t matter if you’re fair or dark, it’s how much warmth your skin has. If you have too much gold or pink to your skin tone, color changes are more difficult. However, there is a perfect tone of hair color in all ranges, from blonde to brunette, for everyone. It’s the colorist’s job to identify whether your brown should be warm or cool, whether your auburn should be as rich as cabernet or as coppery as a penny and whether your blonde should be icy and arctic or like spun gold.

Thanks, Kat! So, there you have it. In the right hands (aka a professional stylist) almost any hair color can be adapted to pretty much any skin tone. And now on to the question of the day: What is Scarlett’s best hair color? Weigh in below.