PARIS — Mellerio dits Meller has been creating jewelry and precious objets d’art since the Renaissance, giving it a plausible claim to being the oldest jewelry house in the world.

Yet last month, it did something new: The company introduced a timepiece unlike any it had released before — the mechanical M Cut watch.

“It’s our first automatic watch,” said Laure-Isabelle Mellerio, 52, the company’s chief executive and artistic director. Since taking over the direction of the family business following her husband’s death in 2018, Ms. Mellerio has been intent on finding ways to reach a new young clientele; she decided that a high-end watch might appeal.

In recent years, Mellerio has produced watches, but they have all been quartz models. The new collection of M Cut watches, by contrast, boasts a mechanical movement made in Switzerland by one of the expert manufacturers in the watch town of La Chaux-de-Fonds. Ms. Mellerio would not identify the manufacturer, but the movement it produced is a widely used ETA 2000 caliber, which is visible through the timepiece’s open back.

The watch has a date window and is water-resistant to a depth of 30 meters, or almost 100 feet. Prices range from 7,600 euros to 17,600 euros, or the equivalent of $7,760 to $17,975.

As with most of Mellerio’s creations, what’s new has been balanced by what’s historic.

In this case Mellerio tradition is obvious in the watch’s egg-like shape, a form that has been a feature of the house’s watches since the early 1990s. “It’s based on the Beau Sancy,” said Côme Mellerio, 28, the house’s international business manager and the one member of the 15th generation of Mellerios who is working in the family business.

The Beau Sancy, he explained, is a 34.98-carat diamond renown not just for its size, but for its unusual shape. The gem came by its name through one of its early owners — the French diplomat Nicolas de Harlay, seigneur de Sancy. The diamond later became the centerpiece of the crown that Marie de’ Medici wore for her coronation as queen of France in 1610.

While Mellerio did not create the crown or even own the stone (which was last heard of in 2012 when it was sold at a Sotheby’s auction to an anonymous buyer for $9.27 million), the jewelry house has long had special connections to Marie de’ Medici, who played a major role in its history. “On Oct. 10, 1613, she granted Mellerio a license to sell their wares at court,” Ms. Mellerio said.

The queen also Frenchified the jeweler’s name, adding “dits Meller” (meaning called Meller) to its title to associate the jeweler, founded in 1515 in the Lombardy region of Italy, with its adopted home of France.

Today, the Place Vendôme in Paris is known as the home of luxury jewelry and watch houses; Mellerio was the first jeweler to settle in the neighborhood. “When Napoleon created the rue de la Paix, my great-great-grandfather wanted to be the first jeweler to be there,” Mr. Mellerio said.

So in 1815, Mellerio opened its boutique at No. 22. In 1851, the store moved across the street to No. 9 — “the sunny side, so there is more traffic,” Ms. Mellerio noted. The shop has been there ever since, with its workshop in the same building.

Ms. Mellerio got up from her desk in her office at the back of the boutique and pulled a large leather-bound ledger from a bookshelf. She opened the pages, tinged brown with age, to show the design sketches of some of the timepieces — or rather, the bejeweled settings for Swiss-made movements — that Mellerio had created over the centuries. “We also made pocket watches, and bracelets,” she said, and turned to sketches of watches set in bejeweled gold bangles.

In 1993, Mellerio started making wristwatches in the shape of the Beau Sancy, powered by Swiss-made quartz movements. The designs ranged from clean-cut steel cases on leather straps to gold cases with guillochéd dials. One dazzling ladies’ model now on the website is the Medicis Watch, a diamond pavé timepiece priced at €90,000.

By contrast, the M Cut models are unisex, Ms. Mellerio said, measuring 36.95 millimeters by 30 millimeters. Cases come in steel, white gold or yellow gold; dials in white, black, navy or silver; and straps in various colors of calfskin or alligator leather with metal buckles that also mimic the shape of the Beau Sancy.

Like the M Cut watches, Ms. Mellerio said, she designed the house’s Muse jewelry collection with a young audience in mind.

“I look at people in the streets, and I see people wearing lots of little necklaces, layering them,” she said. “I want to introduce these young people to wearing Mellerio.” The Muse collection draws on the house’s design motifs — including crosses, blossoms, fleur-de-lis and the ovoid Beau Sancy shape — but in pieces so small and delicate that they appear to be almost sprinkled on gold chains or lightly dusting bracelets, earrings, rings and pins.

A new Muse line, called Riviera, was inspired “by our customers from the 1900s going to the beach,” Ms. Mellerio said, referring to one of the boutique’s display cases containing a preview of the designs, along with some vintage postcards from the South of France. The line is to be introduced officially in September.

Some of the pieces have little emeralds to call to mind the region’s casuarina pine trees, and tiny diamonds “like the foam at the crest of a wave,” she said, set into gold wire that has been bent into the shape of, yes, the Beau Sancy.