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...

Sally Hansen Color Therapy, Ja-Cozy, $7. An argan oil-infused nail polish in the most cheerful shade of cobalt.

OPI Nail Lacquer, Never a Dulles Moment, $8. OPI's latest collection, inspired by the show "Scandal," includes this opaque, sunny yellow.

Orly Gel FX Gel Nail Color, Invite Only, $5. Green is the 2017 Pantone Color of the Year; why not try a Kelly green mani?