Butter London's custom-mixed pepto pink polish created for the Victoria Beckham Dresses show has become a collaboration between the two that will launch this spring. Courtesty Photo

It's been the week of the backstage nail polish launch.

Priti Polish's shade for Elise Overland. Courtesy Photo

New York Fashion Week Spring 2011 kicked off with CND's much buzzed-about polish partnership with Jason Wu, and more designer and nail brand collaborations unfolded as the days rolled on, with names like Victoria Beckham, Bill Blass and Prabal Gurung thrown into the nail lacquer mix.

So why all the polish love from designers who usually keep the focus on the clothes?

"Nail polish and nail style is an affordable luxury accessory," says Jan Arnold, co-founder of CND. "It's one of the few accessories not previously branded by designers."

CND's launch with Wu of five timeless shades inspired by iconic women will go on sale in Spring 2011, with the highlight being the limestone-gray Miss Wu shade that the designer himself refers to as his signature color.

"With my clothing, there's always that masculine-feminine contrast. The evening wear is so extravagantly feminine that in the day wear, it's always a little tomboyish mixed with a quirky take on American sportswear, and I think this color says it all," said Wu in an interview with Arnold earlier this week.

While CND's launch was strategically planned in advance, other collaborations can happen on the fly.

We sat next to creative director of Butter London Nonie Creme at the Betsey Johnson show Monday night, where she divulged that the custom-mixed pepto pink polish she created on the spot for Victoria Beckham's presentation the day before was an instant hit with the former Spice Girl.

The Miss Wu shade created backstage at Wu's Fall 2010 Show. Courtesy Photo

A couple of days later, news emerged that Butter London and Beckham would collaborate on the shade, and offer it as an exclusive nail polish for spring.

"Designers have really started coming around to the importance of the nail area when showing their collections on the catwalk," Creme tells StyleList.

"I work with each designer to really look at not only the collection, but their consumer as well. Who is their 'woman?' Make up can be mixed and customized on site, and so nails should be as well - it ensures that the show look is utterly on the mark," adds Creme, who is known for blending shades just moments before show time at most of the collections she works on.

Organically-sourced nail polish line Priti NYC worked with two designers this week, using the 1960's inspired pale mauve Mushroom Flower at Elise Overland that will be available come spring, and the bronzey-silver Water Soldier for Bill Blass that will launch online in just a few weeks.

With a name derived from the Sanskrit phrase for love and satisfaction, the brand names its polishes after the plants and flowers they resemble, with formulas that are free of toluene, DBP, formaldehyde, all known carcinogens and petroleum.

Sally Hansen -- the nail brand who has brought the collaboration concept to the mass market -- will collaborate with Tracy Reese for the tenth consecutive season in a row, as well as forge a fresh partnership with designer Prabal Gurung.

"In a tough economy, women know they can experiment and be in style with nail color, inexpensively. Designers like Tracy Reese and Prabal Gurung have a unique gift in combining the latest colors in a unique and very feminine way," says Bill Boraczek, senior vice president of Sally Hansen global marketing.

Sally Hansen's line with designer. Tracy Reese. Courtesy Photo

The seven shades made in conjunction with Tracy Reese will feature that brand's new all-in-one manicure formula. That means a base, growth treatment, color and top coat in each bottle. Reese also debuted stickable nail color called Wicked Bamboo that can be quickly smoothed onto nails for up to ten days, and requires no drying or setting time.

And at Prabal Gurung, the designer blended bold shades of color for nails as a contrast to the sharp tailoring and minimalist silhouettes found in his collection. Look for shades of apple red, strawberry mango and sky turquoise to debut in the exclusive polish line.

Sally Hansen's line with designer Prabal Gurung. Courtesy Photo

All limited-edition nail lacquers will be available for $6.99, and the nail art strips for $9.95, at drugstores nation-wide starting in the spring so that you can rock the top trends on your fingertips.

Want to score the luxury polish trends for cheap this Fall? Check out our round-up of the best knock-offs.