The Parisian designer Lauren Rubinski likens her new store, Rubirosa’s, to “a candy shop for adults.” Inside the 450-square-foot boutique on the Left Bank’s Rue de Grenelle, the custom-made, ebony-veneered shelves are stacked with plush cashmere sweaters in 15 colors and neatly folded cotton poplin shirts, pajamas and boxer shorts in more than 35 vivid hues, from soft mint to deep crimson. Rubinski, 40, considers her debut collection a much-needed antidote to the prevailing pared-down, neutral look. “Every store has black, navy blue, blue stripes — that’s it,” she says. “People are fed up with it.” So far, her assessment has proved correct: After opening the boutique this past June, she hit her projected annual revenue in just six weeks, she says.

Retail is in Rubinski’s DNA. Her paternal grandfather manufactured tailored jackets and coats for Arnys, the luxury Parisian menswear store favored by politicians like François Mitterrand, and sold poplin to the Vatican. Her father, Bruno Rubinski, had two multibrand boutiques, one under his own name on Avenue George V and a second in Saint-Germain called Wallaby. Both closed about three decades ago. Lauren — who was named after Ralph Lauren — started designing fine jewelry in her early 20s and launched her line Pristine in 2009. Her first point of sale was the cult Parisian store Colette. In 2020, she established her namesake collection — weighty-looking, handcrafted necklaces and bracelets in 14-karat gold, enamel and diamonds — which is sold by luxury retailers like Net-a-Porter.

Rubinski does offer accessories at Rubirosa’s — soft leather loafers, some embossed with crocodile print — but her jewelry is not among the wares. “Here, I wanted to have pieces that were great quality, but alsojuste,” she says, using the French expression for fairly priced. “We have all kinds of clients, and that was important.” The shop’s signature shirt — a menswear-inspired cut with a straight French collar, available with or without piped trim — starts at about $360.

On a gray December day, while Maria Callas at La Scala plays over the shop’s sound system, Rubinski is wearing a deep lilac version of the shirt with jeans, an oatmeal cashmere sweater, black croc-embossed loafers with white socks and one of her signature articulated gold bracelets. “I’m the first customer for all my businesses — I don’t do anything I wouldn’t wear myself,” she says, admitting she owns over 200 Rubirosa’s shirts and more than 10 versions of the shop’s loafer.

While Rubinski describes herself as “a black belt shopper,” she found herself, in recent years, browsing and purchasing mainly online. “I don’t go to stores anymore because I don’t like the shopping experience: They’re too large, there are too many products and everything is too expensive and of such poor quality,” she says. With Rubirosa’s, her goal was “to bring back the small shop, the kind you used to find when you traveled in Italy or France, where you would say, It’s on the little street to the left, then to the right, and inside they have the best of everything.”

To help execute her vision, she recruited Louis Charles Aka, a creative director and interior designer in Paris. “I wanted to create something so visually desirable that even if you don’t know of the brand, you’ll want to go into the store,” he says. That meant covering the facade in burnished wood with large brass lettering and hanging pale yellow, scalloped-edge balloon shades in the front window. Inside, the carpet is lipstick red, the ceiling is a soft pink, and there are biscuit-colored velvet banquettes and pale-blue fitting rooms. “It’s like a beautiful old yacht,” Aka says. On the walls are portraits he commissioned from Medarto, an Ivory Coast-based artist. They feature famously well-dressed men, ranging from the despotic (Mobutu Sese Seko) to the beloved (Luciano Pavarotti). Aka can also claim credit for the name of the brand: While reading a biography of Winston Churchill, he learned about Porfirio Rubirosa, a 20th-century Dominican diplomat — and a handsome and stylish playboy whose wives included the socialites Doris Duke, and Barbara Hutton, and who had an affair with the actress Zsa Zsa Gabor.

The portraits may be of men, but the entire Rubirosa’s line, which is made in Spain, is unisex, with sizing ranging from extra small to extra large, and Rubinski says her customer base has been equally split between men and women. There has even been some twinning: “A New York couple on their way to the airport bought matching fuchsia pajamas and red slippers to wear on the plane,” she says. Other clients have snapped up a single style in three colors. To meet that level of demand, Rubinski is now looking for a second site on the Right Bank, but while there has been interest, e-commerce is currently not in her plans. “I’m sorry, we don’t deliver,” she tells fans who reach out on Instagram. But, she says, “I always reply politely: See you soon in Paris.”