This is hardly consolation to Chanel, which in November sued the RealReal in federal court, charging that the consignment company has sold fakes and misleads consumers into believing it has an affiliation with the French fashion house. Only Chanel personnel can tell what is truly Chanel, says Chanel.

“They are trying to stop the circular economy,” responded TRR in a statement, adding a motion to dismiss the suit, still pending.

“Chanel is holding on to old ways,” Ms. Wainwright said. She has collaborated extensively with Stella McCartney, a label known for its ecological consciousness, and has cordial relationships with Kering, which owns Gucci, Saint Laurent and Alexander McQueen , as well as the Parisian behemoth LVMH (Celine, Dior, Marc Jacobs etc.). “No other brand is so afraid to embrace us,” she said. “I don’t think they understand: The secondary market supports the retail market. When people sell things on our site, they go buy new. You wouldn’t buy a car if you couldn’t resell it!”

From Flops to Fops

Ms. Wainwright is herself a model of personal refurbishment.

For a long time she was best known in Silicon Valley as the C.E.O. of Pets.com, with its jabbering sock-puppet mascot the most mocked of e-commerce 1.0 failures. “It was as dark as it can get,” Ms. Wainwright said of that period, which included her then-husband asking her for a divorce. “People were horrible, just horrible.”

Realizing the internet wasn’t going away, she began a short-lived online magazine for women over 35 called SmartNow (“I’m not good at naming,” she said, “but I’m good at setting objectives.”) and mulled ventures related to cosmetics or health care. “It’s like, ‘Do I want to be in the natural-food business?’” she remembered thinking . “No.”

Then one day Ann Winblad of the venture capital firm Hummer Winblad, a mentor, took her along on a shopping trip to Head Over Heels, a consignment boutique in Menlo Park, Calif. With tasteful merchandising, the owner had managed not to “break the romance of the brand,” the way that other cut-rate outlets did, Ms. Wainwright observed. “Whenever I would give stuff to Goodwill it always made me sad,” she said. “You don’t want to see your beautiful things in a heap or wrapped up on a hanger.”