Why you need it: Greige polishes seemed like a passing fad in the late 2000s, but we're glad they stuck around. Neutral polishes like gray, beige, white and cream are more noticeable than pale pink or nude, but versatile enough to work with almost any outfit.

When to wear it: It's great for every day, as your go-to work-week polish, with bright clothing (to avoid clashing) or a neutral ensemble (for a chic monochrome look).

Try...

OPI Nail Lacquer, You Don't Know Jacques!, $8. This cult favorite shade has been credited with kicking off the greige fad.

RMS Beauty Nail Polish, Luminizer, $15. RMS Beauty's cult highlighter has been released in polish form and gives nails a semi-sheer, pearlescent finish.

Smith & Cult Nailed Lacquer, Stockholm Syndrome, $18. Smith & Cult, the nail polish choice of cool girls everywhere, just came out with this cool (natch) gray.

Why you need it: Chanel made deep, dark nail polish a thing when it released one of its signature shades, Black Satin. Once the domain of misunderstood teenagers and rock stars, dark nail polish has transformed into a perennially cool accessory of the chic and trendy. The ideal dark polish, if not black, is just a few shades shy of it.

When to wear it: Pretty much anytime between Halloween and Easter; when you're in the mood for drama; when you're in a bad mood and want to stay there.

Try...

OPI Nail Lacquer, Lincoln Park After Dark, $8. This black-plum polish is a perennial favorite in nail salons everywhere -- maybe the sing-song name has something to do with it.

Sally Hansen Complete Salon Manicure, Dark Huemoor, $7. Halfway between blue and black is this intense crème enamel, perhaps the coolest nail polish you can find at a drugstore.

Deborah Lippmann, All Night Long, $20. Basic black polish is updated with a beautiful, bronze-y shimmer.

Why you need it: There comes a time every spring or summer when a flaming orange, bright blue or flamboyant violet mani-pedi just makes sense. Embrace the moment -- especially if you're going on vacation and/or wearing a sundress with sandals.

When to wear it: At the beach, at the pool, and whenever you need a dose of optimism.

Try...