He certainly is passionate about horology these days, but Thomas Fleming wasn’t always a fan of watches.

“I thought they were kind of useless,” Mr. Fleming said during a phone interview from a makeshift office he had set up while visiting his parents at their house in Pebble Beach, Calif., “because if everyone has a phone, why would they need a watch?”

And, “why would I spend a lot of money for one when it doesn’t do anything that I need?”

Yet when a close friend received a TAG Heuer Aquaracer for his 18th birthday, Mr. Fleming, 26, who was then 18 himself, began researching watches. And his opinion quickly changed.

The combination of “being fully mechanical, and all the different designs, and also just the storytelling aspect that they have,” he said. “I think that all sort of hooked me in.”

Now, Mr. Fleming is preparing to release the Series 1 Launch Edition, the first timepiece from Fleming, his watch company. The plan is for the timepiece to go on sale within the next few weeks. The look of the 38.5-millimeter mechanical watch is reminiscent of many classic, clean-lined men’s designs. The dials of two of the model’s three iterations include guilloché, or engraved, details; one has textured embellishments in hand-hammered metal as well. Several additional watch designs are also in the works.

“The wanting to start a brand was there from the very beginning,” Mr. Fleming said, “but I wouldn’t have started one just to do it, just because I thought it would be a fun thing. I wanted to make sure I had some ideas I felt strongly about, that were maybe unique in the market.”

Fleming’s prices are high. The Launch Edition ranges from $49,500 for a tantalum case detailed with navy blue aventurine to $55,000 for a platinum option with three guilloché patterns on the dial. In between, there is a rose-gold model at $53,500. A total of 50 pieces will be made, but nine are to be used for sales and marketing.

Mr. Fleming said he didn’t set out to make such expensive watches. But the caliber of the development team he worked with may explain the result, at least in part. For design, there was Neodesis, a studio in Le Locle, Switzerland, that has worked with Harry Winston and Hublot. The movements were created by Jean-François Mojon, whose movements have been used by Harry Winston and MB&F; and the dials were produced by Comblémine, of which the renowned independent watchmaker Kari Voutilainen is an owner.

Emmanuel Gueit, who designed Audemars Piguet’s Royal Oak Offshore, was impressed by Mr. Fleming, who initially contacted him through an Instagram direct message, and he signed on to work on several future models.

“He has the correct approach to the watch industry,” Mr. Gueit said. “Not so much, “I want to do watches because I want to make money’.”

Instead, “he really went to the watch world and ‘Watch Valley’ and knocked at the door of the big ones.”

For a start-up like Fleming, respected collaborators offer a stamp of credibility. “I don’t know if it’s the key to success, but I think it definitely helps,” said Robert-Jan Broer, editor in chief of the website Fratello Watches.

In addition to working with established watch industry veterans, the brand has another noteworthy alliance: The Norwegian tennis player Casper Ruud is its athletic ambassador, an affiliation Mr. Fleming said was inspired by similar relationships that the likes of Rolex and Richard Mille have with athletes.

Fleming’s next watch, the Series 1 Ghost, will be a lighter, shock-resistant take on its first timepiece, deliberately designed for activities such as, well, tennis. Its release, Mr. Fleming said, is planned next year. (Mr. Gueit is working on it and the Series 2; the Series 3 will be wholly his design. Mr. Fleming has been involved in the design of all the watches, in addition to founding the company.)

Mr. Fleming, who was raised in Alexandria, Va., is the first watch collector in his family. (His father is a partner in a venture capital firm; his mother, an accountant, is retired; and he has two younger brothers.) And initially, his own array was pretty limited: As he became interested in watches, he bought a steel Victorinox and an Orient divers’ watch, and in 2015 he received the Omega Speedmaster that he had asked for as a high school graduation present.

But while he was studying at Stanford University, he began to collect watches — he now has about 75 — from a wide range of brands, from Casio to Patek Philippe. He also immersed himself in watch websites and forums, and started an Instagram account to post photos of timepieces he liked. Through the app, he gradually began to meet other collectors, like James Kong, a watch photographer who became Fleming’s chief operating officer in January. The company’s other two full-time employees are Grace Rood, the chief financial officer, who is Mr. Fleming’s girlfriend; and John Fleming, a younger brother, who is working on several areas of the business.

In his senior year of college, Thomas Fleming started to develop a line of natural soft drinks called Atmos, but even while working on that project, he thought that starting a watch brand would make sense, in part inspired by the popularity of watch microbrands in recent years. He graduated in 2019 with a degree in management science and engineering and established Fleming, which will sell directly through its website and associated social media accounts, in 2020.

Watch industry experts say collectors continue to find small brands appealing. “There’s a lot of interest and demand for microbrands, whether they’re affordable or on the high end,” Mr. Broer from Fratello Watches said, noting that they allow collectors “to be more individual rather than to follow the herd and buy your 10th Rolex or 20th Breitling.”

Mr. Fleming, who is now based in Washington, D.C., said he initially didn’t intend to use his family name for the company. But while checking copyright clearances on potential names for the brand, which is wholly owned by Mr. Fleming with investments from his family, his last name was available and several other choices were not.

“I’d hope if we’re successful, people don’t associate the name with just me but the brand in general,” he said. “They might not know there’s a person named Fleming behind it, which would be great.”