The first time I saw a personalized metal clasp on a watch strap, I thought, “I’ve never seen this before.” I probably was correct.

“We’re the only ones who do it, let’s put it that way,” said Alexander Maroulakis, 35, the co-founder of Atelier Honoré, a business in Luxembourg that specializes in what some people call deployment clasps, but with elevated design.

The idea came about in November 2019. “Timo was visiting me, I was living in Athens at the time,” said Mr. Maroulakis, referring to his business partner, Timo Schoones. “He thought, ‘What about if we allow for a customization option of watches without touching the actual watch, but rather an element of a watch, the clasps, which are usually very standard?’”

On his flight home to Amsterdam, “I started working on it in midair,” Mr. Schoones, 30, said in a recent interview. “When I landed, we had the first draft.” Neither man has a technical background, but Mr. Schoones said he learned how to use computer-assisted design to work on the products.

Atelier Honoré was established officially in July 2022. (As for the name, Mr. Maroulakis, who now lives in Luxembourg, was spending a lot of time in Paris at that time and, he said, “we just liked how it sounds.”) The custom clasps quickly caught the attention of watch collectors. “I’ll be honest, we’ve done pretty much no marketing,” he said. “It’s only word of mouth, and through friends that we know in the industry.”

One of those early enthusiasts was Masaharu Wada, the co-founder of the Tokyo Watch Club and an editor and web producer at Hodinkee Japan. “Watches are personal items that people choose to match their own style and preferences,” he wrote in an email. “While it’s now common among watch enthusiasts to swap out straps, I believe that the next level of enjoyment comes from customizing the clasp. I had two clasps designed with my family crest made at Atelier Honoré — one for my father, who shares my passion for watches, and the other for myself.”