PARIS, France — A gleaming necklace in Boucheron's shop window in Paris's Place Vendome features dozens of lifelike hydrangea blossoms made from mother-of-pearl and diamonds, framing a 43-carat pink tourmaline.

Shoppers who enter the restored 18th-century mansion, which reopened this week after a sweeping restoration by parent Kering SA, can slip out with their purchases via a secret door through the lacquered panels of a Chinese-inspired selling room. High rollers who prefer to stay might even be invited to sleep in a VIP guest suite — operated by the Paris Ritz, no less — featuring views of the Eiffel Tower from the bathtub.

"This is more than just a store opening for France," said Boucheron chief executive Helene Poulit-Duquesne, who joined the brand in 2015 after 17 years at Richemont's Cartier. The Paris square is the world's most prestigious jewellery destination — housing such names as Van Cleef & Arpels, Chaumet and Chanel — and a pilgrimage has become de rigueur for fans of top-end pieces. "This story of the Place Vendome is what we want to tell around the world."

After a push into skateboarding wear and soccer brands like Puma fell flat, Kering is trying to diversify within luxury at a time when targets for acquisition are scarce. A rapid comeback for its flagship brand Gucci, which rebooted with a new designer's decadent aesthetic in 2015, drove shares in the group up 85 percent last year alone. But the relentless pace of growth in Gucci's two-year run has meant the company is more dependent on the brand than ever.

The group helmed by the French billionaire Francois-Henri Pinault is now ramping up investment in jewellery, adding stores for Boucheron and a new high-end jewellery collection for Gucci, as well as expanding its smaller fashion brands like Balenciaga and Alexander McQueen.

Boucheron was founded soon after Cartier and is part of the elite club of French jewellers that produce haute joaillerie, or high jewellery: one-of-a-kind pieces priced from $50,000 to several million dollars, which are handcrafted in Vendome ateliers to show off precious stones and their makers’ most advanced techniques. But while Cartier touted its meticulous craftsmanship to sell a range reaching from super-luxury products down to more modest models like $4,000 Panthere watches and “Love” bracelets in nearly 300 stores around the world, Boucheron remained a lesser-known option, under family management until a sale to Kering in 2000.

Boucheron’s accessible lines, including its best-selling $4,000 Quatre rings, entered the global spotlight more recently. Spokeswomen like the actresses Lea Seydoux of France and Zhou Dongyu of China sport the items — and Beyonce has worn them onstage.

In addition to the renovated base, Kering has opened its first two Boucheron boutiques in mainland China this year and has additional locations in Hong Kong and Macau on the way. While the group doesn’t disclose figures for its smaller brands, a company spokeswoman said Boucheron has been profitable since 2007 and sales have more than tripled since the acquisition. Reports at that time estimated its revenue was €85 million ($97 million.)

Global names dominate categories like high-end watches and handbags, but consumers haven’t historically thought about the brands behind their diamond pendants and gold hoops. A study by consultancy McKinsey found that global brands made up only 20 percent of the jewellery market in 2014 — a figure it expects to double by 2020.

“We see great potential for houses which have an international approach and a distinctive identity,” said Albert Bensoussan, chief executive of Kering’s watches and jewellery division.

Touchscreen panels let visitors to Boucheron’s Paris store swipe through stories about notable former clients including the Countess of Castiglione (who used to live upstairs,) Jane Birkin and Czar Alexander III. But even if the renovation highlights Boucheron’s history, its chief executive is wary of focusing too much on the brand’s pedigree.

As one of the first women to lead a high-jewellery house (head designer Claire Choisne is a similar pioneer,) Poulit-Duquesne is sensitive to the fact that marketing focused on heirloom status or sentimental gestures holds many women back from buying jewellery. “I’d rather to talk to women about style, about how they can use the piece,” she said. “The idea is to unburden the process.”

To make clients feel more at home in the brand’s renovated base, the chief executive opted to remove the rectangular counters and desks where buyers worked through a jewellery purchase across from each other, opting for friendlier, round tables. Saleswomen were allowed to eschew banker-like skirt suits in favor of a softer elegance, choosing from an approved selection of silky jumpsuits and botanical-print dresses.

“It’s an experience,” Poulit-Duquesne said. “Even if you don’t go, it’s important to know that the place exists.”

By Robert Williams; editors: John J Edwards III, John Lauerman and Eric Pfanner.