The New Redheads of Hollywood: Rachel McAdams, Dianna Agron, Elizabeth Olsen, and Coco Rocha

Hollywood is seeing red! Last week, Dianna Agron and Rachel McAdams both surprised all of us by taking their blonde strands to a bold crimson, and now, Elizabeth Olsen, and Coco Rocha are the latest celebrities to give their hair an auburn tint. While Rocha went the fire-engine route, Olsen's change was much more subtle, adding a hint of red to her brunette shade. Considering the red route? Joel Warren of Warren-Tricomi Salons notes that the color is more high-maintenance, but the bold statement it makes is worth it. "Red hair has the largest molecule and is difficult to enter into the shaft of your hair," Warren told us. "To make it last, you need products that help close the cuticle. Try L'Oreal Professionel's INOA salon service, which doesn't have ammonia and won't open the hair cuticle." Additionally, add more color-preserving products into your hair routine, and steer clear of shampoos that contain sulfates, which can strip hair color. "A strawberry blonde on a blonde base will last much longer than a rich auburn on that same base color," he added.

See more celebrity hair makeovers in the gallery!

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