COLOUR ALCHEMY in shade Borealis provides instant iridescence to your hair. Inspired by the aurora borealis, also known as the northern lights – the awe-inspiring reaction of solar flares hitting the earth's magnetosphere – this luminous shade starts at purple before shifting through green and violet. A shade so beautiful and bold, it was the first to sell-out within 48 hours of the COLOUR ALCHEMY launch. Borealis image credit: Getty Images via Forbes.