The pre-owned watch market, projected to total around $30 billion in 2025, has been growing exponentially — to the point that, within five to 10 years, it is likely to account for half of the global watch market, according to Karine Szegedi, managing partner of consumer industry and fashion and luxury at Deloitte. (For comparison, industry analysts estimate the 2021 retail sales of Swiss watches were $50 billion.)

The reasons for the growth of the pre-owned category are actually pretty simple: Since the popularization of the internet in the 1990s, sellers have had easy access to pricing history in a marketplace brimming with opportunities to trade or simply cash in on their timepieces.

Making sense of it all, however, has never been more difficult.

“There’s an almost endless amount of ways a person could sell a watch,” said Eric Wind, a dealer and owner of Wind Vintage in Palm Beach, Fla.

There is the most basic: Posting a watch on Instagram, promoting it with the appropriate hashtags (try #watchforsale) and negotiating directly with potential buyers. The most rarefied: Consigning a timepiece to a live auction in one of the watch world’s three major cities of New York, Hong Kong or Geneva. And in between are retail stores, dealers, online forums, auction houses and collectors’ meetups, to name just a few platforms.

What is clear, experts said, is that droves of watch owners are just discovering the possibilities. “And the more visibility we get, the more people wake up,” said Arjen van de Vall, the London-based chief executive of Watchfinder & Company, an online pre-owned dealership founded in 2002. “‘Hey, I received this IWC pilot’s watch when I graduated and now I want to sell it or trade it in — can I put that toward my next watch purchase?’”

“It’s been really steady gains, but the last 24 months have been quite intense,” he said, “with all the attention we’ve had as an industry.”

If you are thinking about selling a watch, the following tips may help.

Assess the Condition

“The more original and more ‘minty,’ as we say in the business, the better,” Mr. Wind said. “The ‘new old’ stock, never-worn watch with the original box and papers — that’s the holy grail.”

Echoing his fellow dealers, Mr. Wind said any service that altered a watch’s original state, from applying new luminescent material to the dial to polishing the case, potentially decreased its value.

That has been a particularly thorny issue with vintage Rolexes, especially those sent into the company for regular servicing. “You can send in an old watch and they give you a brand-new dial but that can mean the watch is worth as little as 1/100th of what it was worth previously,” Mr. Wind said, adding that many people who inherit their father’s or grandfather’s watch don’t realize this when they seek servicing.

Determine a Price

As with real estate, look at the comparables. Many prospective sellers turn to eBay and the online watch marketplace Chrono24 to get a range of prices for the model they intend to offer (especially if the timepiece is modern, a term that loosely refers to watches manufactured during the past 20 years). Auction house results and resale sites such as 1stDibs can offer additional data.

But none of these sources should be considered definitive. “It’s often just a sixth sense,” Mr. Wind said. “How deep is the market of potential buyers? Is it an easy-to-sell Rolex Datejust, as long as the condition is good? Or is it a Rolex Submariner that’s worth hundreds of thousands of dollars, with a lot fewer buyers?”

Sellers also should understand that prices — particularly on blue chip models such as the Rolex Daytona, the Patek Philippe Nautilus and the Audemars Piguet Royal Oak — have been in flux in recent months.

“Let’s say you looked for a ‘John Mayer’ green dial yellow gold Daytona and looked online for pricing,” said Oliver Smith, founder of Oliver Smith Jeweler, a watch and jewelry retailer with locations in Scottsdale, Ariz., and Aspen, Colo. “You’d see prices from $80,000 to $130,000, which is super confusing. The $130,000 seller has not reset his price to the new market, which is $80,000, so you have to be careful.”

Choose a Method

The optimum platform to sell a watch depends on the make, age and value of the timepiece, as well as how much effort the seller is willing to put into the process. (In all instances, having clear photographs of the front, back and side of the timepiece will be important, partly because sharp photos make a good impression.)

Kathleen McGivney, a New York watch collector and co-founder of the RedBar global collector group, said she appreciated the convenience of selling through pre-owned platforms such as Analog:Shift, Crown & Caliber, WatchBox and Watchfinder & Company, even though all those businesses would take a cut of the proceeds.

“I could probably get more money if I put in the time and effort to do it on a direct sales platform,” she said, “but for me, it’s worth paying someone else to do it.”

For more rare or vintage watches, Scott Heileson, a patent lawyer based in Northern California who collects Marine Nationale (French Navy) watches, recommended that sellers use social media to network within the category.

“If I was going to sell a Marine Nationale watch, the first thing I’d do is look for a Marine Nationale influencer,” Mr. Heileson said. “I’d message them, ask if they’re interested, or if they knew anyone. Just broadcast it.”

Brand-specific forums are traditional places to sell watches on the internet, and they still present a good option for sellers who want to connect directly with potential buyers.

“But don’t just list on a random forum,” Mr. Heileson said. “Go to where the Panerai folks are. Forums are nice because you can set your own price, there are no fees, no escrow. You can see past transactions. The seller posts a few photos and buyers can either message you through the forum or typically they email you directly.

“I like to get on the phone,” he added. “I want to be a helpful seller. And if somebody is a little cagey or acting weird, you should pay attention to that.”

Consider Auctions

For sellers who may not be familiar with the watch trade, eBay has been a popular place to offer a timepiece, either through an auction listing or the site’s “buy it now” feature — which supports the company’s statement that during 2021 a watch was sold on its platform every eight seconds.

The 2020 introduction of the eBay Authenticity Guarantee, a free post-sale authentication service for watches listed at $2,000 or more, has helped longtime eBay sellers such as Katrina Hess, co-owner of Hess Fine Auctions, because it provides protections against scams.

“People who think eBay is just a flea market must understand that it has matured into perhaps the most ethically sound and safe place to sell on the internet,” Ms. Hess wrote in an email.

The watch auction universe has swelled in recent years in step with the growth of the overall watch market, and scores of more traditional players, many of them small and regional — including Doyle, in New York; Heritage Auctions, in Dallas; Clars Auction Gallery, in San Francisco; Ineichen Auctioneers, in Zurich; Skinner, in Boston; and Bukowskis, in Stockholm — have become eager for consigned watches.

Their online auction counterparts also are rapidly multiplying. The digital watch auction world now includes sites such as Loupe This, A Collected Man, Catawiki, Dial + Bezel, Doublewrist and Bezel Brothers, and there are aggregator websites such as Invaluable and LiveAuctioneers.

At the top of the selling pyramid in terms of prestige and sales volume, however, remain the established auction houses — Bonhams, Christie’s, Sotheby’s and Phillips — whose live sales feature some of the most sought after, and elusive, watches in the world.

Sellers must pay the house as much as 15 percent of the hammer price, what is called the seller’s fee or vendor’s commission. But what they give up in terms of money and time — it can take six months or more from the date of consignment to receive payment — they get back in exposure to a global audience of important collectors.

Paul Boutros, Phillips’ head of watches in the Americas, said the house rejected “about 90 percent of the watches that are presented to us,” but the house’s standards had less to do with price than many sellers might think.

“We’ve offered watches as low as $500,” Mr. Boutros said. “If it’s an interesting watch, even if it’s lower value, we’re happy to offer it, if we think our clients will enjoy it.”

Closing the Sale

For a direct sale, the final steps involve receiving payment and shipping the watch to its new owner. Mr. Heileson said he preferred to conduct transactions through PayPal and advised sellers to wait until the money arrives in their accounts before shipping watches. (Venmo also may work for some transactions.)

“You need to be clear in your listing that the buyer will need to cover the fees,” he said. “The same goes for shipping, particularly for lower price ranges.”

When it comes to pricier watches, a wire transfer is the way to go, Mr. Heileson said, because it affords the seller some protection. “If I take PayPal for a $1,000 watch and the deal goes south for some reason (buyer says they didn’t receive it or that it was damaged or didn’t match description), my day to day won’t change much while that $1,000 is in limbo,” he wrote in a follow-up email. “On the other hand, as some people are doing now, if you’re liquidating the collection to buy a house, and the watch is in the $30,000 range, you’d want the certainty of a wire to make sure that money is something you can count on not getting tangled up in drama.”

Sometimes, though, transactions happen under much less formal conditions. In 2015, for example, Mr. Heileson bought some Marine Nationale Tudor watches from a seller and paid for them in cash at Paris Charles de Gaulle Airport. “I had the cash in a bag and handed it to the guy, and said, ‘Do you want to count it?’” Mr. Heileson recalled. “And he said ‘No, if it’s not all there, we’ll never do business again.’

“It was old school, your word is your bond, and I love that,” Mr. Heileson added. “When you buy, they say you’re buying the seller. But you’re also buying the buyer. Always trust your gut.”