Why you need it: Ancient Egyptians wore nail polish, but only the upper echelons of society were allowed to paint them red. To this day, red nails are a symbol of timeless sophistication. A true red polish -- one that reads neither cool (blue) nor warm (yellow) -- can always be counted on.

When to wear it: Anywhere, anytime, especially when you want to feel put-together and powerful -- at a job interview, or on a first date.

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Revlon Nail Enamel, Cherries in the Snow, $4 Revlon introduced red nail polish to market in the 1930s with this shade. This cool red crème polish remains a best-seller.

Dior Vernis Gel Shine and Long Wear Nail Lacquer, Rouge 999, $27 The neutral undertone in this Dior classic makes this polish look smashing on any woman.

Chanel Le Vernis Nail Gloss, Rouge Radical #530, $28 This stunning new shade from Chanel is translucent in the bottle, like beautiful strawberry jelly. Apply one coat to nails for a sheer wash of poppy red; apply two coats to get an intensely shiny, fiery red.

Why you need it: Why do you need red polish and deep red, you ask? Oh, child... If a red polish is tried and true, appropriate for any occasion, then deep red is its slightly moodier, less predictable sister. You can't wear it with everything, but when you do wear it, you'll feel sexy, feminine and tough.

When to wear it: With a dressy or edgy outfit, especially in fall and winter.

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Chanel Le Vernis Longwear Nail Colour, Vamp, $28. Burgundy bordering on black, this polish was a must-have in the mid-1990s, and was recently re-released due to popular demand.

NARS Nail Polish, Chinatown, $20. It's hard to imagine this cult-favorite oxblood enamel looking bad on anyone.

Julep Nail Color, Scorpio, $14. This bordeaux polish from Julep's new Zodiac Collection is sprinkled with a purple-y red shimmer for a look that's edgy and modern.

Why you need it: Sometimes, you want the attention off your nails -- but you don't want to go totally naked. Nude nail polish is the best color for an understated mani, and it makes raggedy nails look about a million times better. The right nude nail polish doesn't look like polish at all -- just beautiful, clean, shiny nails.

When to wear it: For conservative occasions, or to contrast a bold outfit or statement makeup.

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