Frédéric de Narp had been president and chief executive of Cartier North America for only two months when he was accosted by four shoppers in the company’s Fifth Avenue flagship store.

They were all members of the same family, two pairs of sisters a generation apart. “Everybody goes shoom,” recalls de Narp, sticking out his wrist and yanking up his suit sleeve. On each woman’s wrist was a gold bangle studded with screw heads, first designed in 1969 and inspired by medieval chastity belts—Cartier’s Love bracelet.

It was the sort of moment that makes the hearts of luxury marketers pound. The group told de Narp that every woman in their family had her own Love bracelet. When the men in the family got engaged, their fiancées received one. “It’s our symbol, inside the family, of love,” one of the women said.

Designers dream of creating the next Burberry trench, Hermès scarf, or Tiffany six-prong diamond solitaire ring—fashion classics that appeal across generations with a magical combination of elegance, timelessness, and flair. An iconic item can supply a consistent revenue stream for brands and serve as a counterweight to fickle trends. And price is no object when an item’s image is considered priceless. A men’s double-breasted Burberry trench is $2,150. A yellow-gold Love bracelet is $2,975, and Cartier sold 5,000 in the U.S. in the first two months of 2007. That’s $15 million worth of Love.

“A classic = $$$$$$$$$$,” writes Simon Doonan, creative director at Barneys New York, in an email. “It also keeps a brand in front of the consumer, which results in more $$$$$$$.”

The Love bracelet, which locks onto the wrist with a golden screw, is the bestselling item in Cartier’s collection. It has turned up on celebrities and in place of engagement rings for society couples. Matriarchs on the Upper East Side and in the Eighth Arrondissement wear them stacked three deep. The bracelet remained nearly unchanged for 37 years, but now Cartier is taking a full swing at its marketing potential. In 2006, the company made it the center of a major ad campaign and expanded the screw motif into a full jewelry line, including earrings, necklaces, special-edition charity bracelets, and a 96-carat diamond-and-white-gold cuff (retail price: $285,000). This April, a second Love collection will debut.

It is perhaps a perfect moment for such an expansion, a moment when Americans are particularly susceptible to the spell that an iconic item can cast. (See more in the slideshow.)

“Classics are coming into focus again,” says David Wolfe, creative director at the Doneger Group, a retail consultancy based in New York. “People are scared about social security, the environment, and the geopolitical situation. We are looking for security. And everyone in the world wants to look good to their peers. Classics give people the sense of assurance they are looking for.”

Some items now considered classic were surprises; for example, the Burberry coat started as a garment for British soldiers to wear in the trenches during World War I. “As it was never designed as a fashion piece, it carries the unique label of being a true iconic garment that is functional,” says Christopher Bailey, Burberry’s creative director. But in many other cases, luxury icons were created very purposefully. “In the new luxury category, retailers have to have an item that I call the vision of emulation—a highly desired badge, something recognizable from 50 yards away, that creates a collector phenomenon,” says Michael Silverstein, a senior vice president at the Boston Consulting Group’s Chicago office and author of Treasure Hunt: Inside the Mind of the New Consumer. “The great merchants that invent these things have an idea what they’re doing with design, branding, logo,” Silverstein says. “Very few are accidents.”

Yet ask how the companies were able to make classics happen and the response resembles a typical promotion on Hermès’ website, in which a mustachioed magician pulls a bright scarf from a hat: “Abracadabra, sumptuous silk scarves!” Silverstein estimates that 50 percent of Hermès’ profit comes from duty-free airport shops, which are heavy on ties and scarves.

Tiffany, the diamond authority, calls on the otherworldly to explain the allure of its diamond engagement rings. “The beauty of the ring and of iconic items is their ability to take on a different meaning for each woman who has one,” says Linda Buckley, vice president of media relations. “There’s something magical about it.”

Instant access to a club of well-dressed peers, kinship with celebrities—yes. But the real magic happens on the bottom line.