It was really only a matter of time. Besties Gwyneth Paltrow and Stella McCartney, shown at Goop's Hamptons party this summer, are teaming up on a capsule collection for Goop. Goop is, of course, GP's lifestyle Web site known for recommending very luxe, very expensive everything.

The collection is going to feature investment pieces created by McCartney and chosen by Paltrow. Since McCartney is a designer and Gwyneth is... choosy.

"I think of myself as a woman who is a lover of beautiful things," Paltrow told Vogue. "I'm very specific about my taste. The role I want in a partnership is curating a collection as opposed to taking a designer point of view. I can tweak a blazer and make it the perfect blazer. It's being able to fulfill what my ideal things ought to be."

Unsurprisingly, Stella considers Gwynnie to be a muse: "I have quite a lot of admiration for her at so many levels and that's a big part of how I design. Her spirit and inner beauty as well as outer beauty are a big inspiration for me. I draw from that every day from all my friends," she told WWD.

Items in the collection will include McCartney staples like a black blazer, black jeans and black wool trousers, as well as a charcoal grey knit jumpsuit and several exclusive handbags including her new Beckett bag in black, gray and white. Prices will start at $795. As they teased on Goop's Facebook last week, the collection will debut September 12.

"We complement each other," Paltrow told WWD. "It was the right time. We're very close friends. We were bringing two worlds together and it was important not to force them."