Philippe Stern, who inherited one of the world’s leading luxury watch brands, Patek Philippe, and overcame an existential threat to Swiss watchmaking from cheaper, more accurate quartz watches in the 1970s, died on June 14. He was 88.

The Geneva-based Patek Philippe, where Mr. Stern was president from 1993 to 2009, announced his death. No details were provided about the place or cause.

As the third generation of his family to run Patek Philippe, Mr. Stern introduced new models that pushed the technical boundaries of mechanical watchmaking. He also marketed $40,000 handmade watches as a status symbol — a Mercedes-Benz for the wrist — and helped stimulate a market of passionate collectors who pursued their quarry across enthusiast magazines and websites.

Mr. Stern “was the guardian of a vision that helped shape the entire contemporary watchmaking industry,” according to one of those websites, Italian Watch Spotter, after his death.

In Swiss watchmaking, the 1970s became known for “the quartz crisis,” which followed the 1969 introduction by the Japanese company Seiko of the first electronic wristwatch to use a quartz crystal oscillator to keep time.

These watches were significantly more accurate than mechanical timepieces produced by heritage Swiss firms, whose products were threatened overnight with obsolescence. As Japanese and American quartz-crystal watches dominated the market, employment in Swiss watchmaking fell disastrously from 1970 to the late ’80s.

The brands that survived moved to the luxury end of the business, promoting craftsmanship and an aura of prestige in a mechanical watch costing thousands of dollars. Mr. Stern, who became general manager of Patek Philippe in 1977, was a principal architect of this reinvention.

That year, he oversaw the introduction of the 240 Caliber, a new design for the inner mechanics of a watch. It packed 152 parts into an ultrathin package that included a self-winding feature driven by a 22-carat gold rotor.

The design “repositioned the automatic watch as an object of elegance rather than mere function, competing with quartz not on precision but on refinement,” according to the website SJX Watches. “It remains one of the most influential movement architectures in postwar horology.”

The company’s identity was embodied in an advertising slogan rolled out in 1996: “You never actually own a Patek Philippe. You merely look after it for the next generation.”

Mr. Stern also promoted the Nautilus, first sold in 1976 and still Patek Philippe’s most famous model. It is a thick sports watch in steel that costs as much as some gold watches. The rounded octagonal shape, resembling the porthole of an ocean liner, was said to have been inspired by Mr. Stern’s passion for sailing.

“When the Nautilus was introduced, the watch industry was confronted with the quartz crisis,” Nicholas Foulkes, author of “Patek Philippe: The Authorized Biography,” told The New York Times in 2019. “Philippe Stern had an incredible vision that mechanical watches would come back.”

Another milestone — more symbolic rather than commercial — was the nine-year development of Caliber 89 to mark the company’s 150th anniversary in 1989. The Caliber 89 is a pocket watch with 24 hands and 33 complications, or functions beyond simple timekeeping. They included a daily display of sunrise and sunset, and a star chart whose hands display the path of Altair, a star after which Mr. Stern named a series of racing yachts.

Only four examples of Caliber 89 were originally made; one sold at auction for $5 million in 2004. Its accuracy — within a second a day — “cannot compare to a quartz watch,” Mr. Stern told The New York Times in 1989. “But the value of the piece is that it is mechanical. Precision is not the most important thing. The tradition of watchmaking is.”

Philippe Stern was born in 1938 in Geneva to Henri Félix Stern and Henriette (Delessert) Stern.

Philippe Stern is the namesake of Adrien Philippe, who joined with Antoni Patek in the watchmaking business in 1845.

Mr. Stern’s grandfather, Charles Stern, and his great-uncle, Jean Stern, who had a business supplying Patek Philippe with watch dials, rescued the firm from insolvency in 1932 during the Great Depression and became the new owners. The company has been privately held ever since, one of the few remaining independent Swiss watchmakers.

In 2014, Forbes estimated the Stern family collectively had a net worth of around $3 billion.

Mr. Stern began his career working for Patek Philippe’s distributor in the United States in 1963. He returned to Geneva three years later, soon rising to general director.

In 2009, he passed the presidency to his son, Thierry, who survives him, as does a daughter, Christine Shrestha-Stern. Complete information about survivors was not immediately available.

Philippe Stern was an avid sportsman. As a young man, he was a member of the Swiss national ski team. As a sailor, he was a multiple winner of the Bol d’Or du Léman Regatta, a 100-mile race the length of Lake Geneva and back. After winning the race three times, in 1980, 1982 and 1984, he was allowed to keep the winner’s trophy permanently.

Mr. Stern also supported his wife, Gerdi, in her passion for sled dog racing, a North American sport embraced in the 1980s by the Swiss. Mr. Stern accompanied his wife and her team of “16 or 18” dogs to races, including the world championships.