Elizabeth Siegel, Allure magazine
Think of it as the anti-ombré: The latest hair-color trend is either blindingly blonde or so dark it's on the verge of goth. We asked colorists for a primer on getting these polar opposites just right.
Who it's for: Natural blondes and light brunettes. "This shade is striking and works on both pale and bronze skin," says colorist Sharon Dorram.
See more: The Best Beauty Products Under $9
The process: If you're already blonde, add baby-blonde highlights. That's how colorist Tracey Cunningham achieved Diaz's shade. "I had to highlight it three times," she says. If you're a light brunette, ask for a medium-blonde base with lots of pale highlights-it may take two rounds with the bleach, but it can be done in one day.
Key products: "Using a good conditioner is crucial," says Dorram. Try Rene Furterer Okara Light Activating Conditioner, which protects against fading with honey extract and vitamin E. "Dramatic color must be glossy," says Cunningham. Biolage Colorcaretherapy Shine Spray has UV filters to keep color bright.
See more: The 6 Most Flattering Haircuts for Round Faces
Who it's for: Women with pale skin or blue or green eyes. And since dark hair reflects light better, it makes damaged hair look healthier.
The process: "On long hair, monochromatic color is beautiful, but if your hair is shoulder-length or shorter, the color needs to be broken up," says Dorram. Ask your colorist to make your base a level four (dark chocolate) and add espresso lowlights, says Cunningham. If you're not ready to commit, try a semipermanent gloss first.
See more: The 10 Commandments of Mascara
Key products: "Find shampoos that won't strip the dark color," Dorram explains. Try sulfate-free formulas, such as Bumble and Bumble Color Minded Sulfate Free Shampoo. And for extra protection, try Finesse Color Lock Hairspray, which contains a water-resistant polymer that wraps around the hair.
Shopping Guide: Biolage, biolage.com for salons. The Body Shop, thebodyshop-usa.com. Bumble and Bumble, bumbleandbumble.com. Essie, essie.com. Finesse, finessehaircare.com. Lancôme, lancome-usa.com. Nuxe, beautybar.com. Rene Furterer, beauty.com. Stila, stilacosmetics.com. Tarte, tarte.com.