Imagine it's Friday night, and you're at the bar tapping your nails on the counter waiting for your next gin and tonic. Your eyes land on the girl standing next to you. Well, not so much her as her hair: glossy, caramel-tinted waves throw haphazardly in a deep side part that, to the untrained eye, would read as God-gifted or sun-bleached from a holiday. But you know the truth: It's the work of a good colourist