"Rich" and "smoky" are words Chaplin and Nawrot use to describe the deep brown color of the moment, a cool espresso. This ashy shade looks striking against pale and dark complexions alike. (Case in point: Anne Hathaway and Adriana Lima.)

The color you need to ask for? Oddly, it's green. "Make sure your colorist is using a green base," says Nawrot. "This will ensure that you have an even, dark brown with no warmth." You can also cool down your color with a DIY green toning product.

Bella Hadid's cool brunette hair draws attention to her gorgeous skin tone and light eyes.

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This deep, light-reflecting shade makes Kendall Jenner's hair appear extra healthy and shiny.

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As temperatures drop, redheads should cool down their color, too. Nawrot and Potempa agree that the ideal red this fall is a "velvety" bordeaux with a violet undertone. "Take inspiration from nature, and look to the changing colors of the trees," says Potempa. "A rich, bright red hue [gives] the feeling of fall leaves."

If your red hair comes from a bottle, get a soft bordeaux effect by asking your stylist to add a touch of violet to your usual hair color formulation. Redheads can also get the look at home. "Choose a dark violet-pigmented shampoo, and use one to two times a week, allowing the shampoo to stay on the hair for 15 minutes," says Nawrot. You'll get a "sheer," "jewel-like" finish.

Potempa points to Brie Larson's cool auburn as a hair color to copy.

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