A few months ago, before nonessential stores were closed, Karen Oberman, a department store personal shopper who lives just north of New York City, bought a timepiece she had admired for a while: a white ceramic and stainless steel Chanel J12 Phantom, a 38-millimeter watch with a skeletonized back.

She purchased it through the RealReal, the luxury consignment website where, over the previous six months or so, she also has bought a Chanel skirt, a sapphire ring and a Saint Laurent leather jacket for less than a fifth of its retail price. (Ms. Oberman would not specify the price for the watch, which she paid for with a store credit. It retails for almost $6,000, but it had been marked down on the site to $3,146.25.)

For Ms. Oberman, the factors that might put some customers off buying a high-end watch on a website — condition, authenticity and whether the timepiece actually tells time — were not a concern. “It’s called trust,” she said, noting that she had bought clothing and jewelry on the site and that “I’ve only been pleasantly surprised.”

Ms. Oberman is typical of a growing number of shoppers who are buying previously owned watches from top-end brands like Patek Philippe and Rolex from fashion-centric websites that are better known for their regular rotation of used Gucci horse bit loafers, Louis Vuitton Speedy handbags and Hermès ties.

Last year, for example, sales of watches priced at more than $10,000 on the RealReal increased by more than 60 percent, according to a representative. And it recently posted its most expensive timepiece: a 47-millimeter Jaquet Droz Bird Repeater Fall of the Rhine watch in 18-karat red gold that was priced at slightly more than $300,000. (The RealReal has closed its U.S. stores in keeping with anti-coronavirus mandates, but its e-commerce operation is still operating despite some workers’ concerns.)

The RealReal, like its counterparts in digital trading, refused to provide sales numbers. But Vestiaire Collective, a Paris-based resale website, said it sold about 40 percent more watches last year than in 2018 — alongside Fendi Baguette bags and blazers by the Row. And Fashionphile, the resale site based in Carlsbad, Calif., and partially owned by Neiman Marcus, said its watch sales increased by 90 percent last year, and it recently listed diamond-studded gold watches by Van Cleef & Arpels, Breguet and Harry Winston, each priced at around $20,000. The pre-worn

fashion website Tradesy also experienced a sharp increase in watch sales last year. Poshmark and the French site Videdressing also offer a large array of watches.

The watch selection on fashion-skewed websites typically includes well-known brands like Rolex and Cartier; on some, those with more niche appeal, including A. Lange & Söhne, Vacheron Constantin and Blancpain, are also featured, along with fashion watches from Versace and Michael Kors. On each site, the presentation, near weathered Bottega Veneta Intrecciato wallets and slightly scuffed Goyard totes, suggests a wearable accessory focused on style rather than an investment to be stored in a safe.

Not unexpectedly, women drive sales at these fashion sites. About 70 percent of the watch buyers on Vestiaire Collective are women, said Bastien Manceau, who oversees the site’s watch business. In contrast, Hodinkee, the watch specialty site, says women account for only about 13.5 percent of traffic on the commerce area of its website.

“We have a lot of women who buy bags, they buy clothing, and they also buy watches in the top brands,” Mr. Manceau said in a phone interview. “It’s not only brands like Rolex and Patek or Omega, but also Hermès, Cartier and Chanel: a lot of brands that are quite small on the market, but on the site, they are big brands in other categories and in watches as well.”

Nonetheless, watches also attract men. Henri Keates, a Paris-based financial auditor at Ernst & Young, bought a sleek IWC Portofino about a year ago on Vestiaire Collective after admiring his friend’s Jaeger-LeCoultre Reverso, bought on the site for around half its retail price.

He said he had been checking the website weekly and bought a black Acne Studios cotton jacket a few months ago. “It wouldn’t have occurred to me to buy secondhand clothes or objects, but now it’s the other way around,” he said in a phone interview. “I always look to see if the product exists in secondhand.”

Mr. Keates paid about 3,000 euros ($3,250) for his watch, which he estimated was 40 percent less than it would have cost if it were new. Such comparatively low prices are, of course, the lure for many customers.

A gold Patek Philippe Calatrava from the 2000s, listed on the RealReal at around $10,000, is about half the price of a current model in one of the brand’s boutiques. And on Tradesy, a small rose-gold Cartier Tank Solo was recently priced at $3,860, about $1,000 less than a comparable new timepiece.

As Ms. Oberman said about her Chanel watch, “I wear other good watches, but at the price, it was — what can I say? — a deal.”

A bargain, however, isn’t every customer’s motivation. “There’s also the consumer that wants hard-to-find items, like steel sports watches from the top makers, that are just unattainable at retail,” said Reginald Brack, a watch and luxury analyst at the NPD Group, a marketing research company. “The only place to buy them is on the secondary market.”

The concern for many shoppers, as it is with all types of designer goods, is authenticity. It’s worrying brands as well. Chanel filed suit in 2018 accusing the RealReal of selling counterfeit versions of its bags; it has not been settled, although several of Chanel’s claims were dismissed by a judge last month.

“As the case moves forward, we’re confident the evidence will demonstrate the lack of merit in the few remaining claims,” a representative for the RealReal said in a statement.

Most consignment and resale sites promote their goods’ authenticity. For example, when a user logs onto the RealReal, the tagline “Authenticated Luxury Consignment” comes up.

Many fashion consignment sites typically check items for authenticity, including timepieces. The RealReal has staff watchmakers, overseen by a former service manager of a Fifth Avenue Rolex boutique, that inspects every timepiece it sells, even comparatively low-price options from Kate Spade and Tissot. Fashionphile said it does not carry certain brands its staff members have not been trained to authenticate, like Blancpain.

On some sites that serve as a third-party platform for sellers, like Vestiaire Collective, a watch is inspected after it is sold; if it does not appear to match its description, the sale is canceled.

Yet unlike a Chanel bouclé jacket or Celine wallet, watches need to be more than just authentic; they need to keep time accurately. “It’s really caveat emptor — buyer beware,” Mr. Brack said. “You may buy something that needs a full service that could be very costly.”

These retailers also offer different type of separation: the option to resell a watch.

“You don’t have to own it for a lifetime, although it may last a lifetime,” said Patricia Stevens, who oversees the RealReal’s fine jewelry and watches. “As your tastes change, you can upgrade or change something out for something new.”