The bespoke shirt once seemed to be the preserve of two types of men: the landed aristocrat who never had to shop (how frightfully common!) because his Savile Row tailor had his measurements memorized, and the frugal traveler who happened upon some back-alley, ready-in-24-hours shop in Hong Kong.

In this era of mass luxury, it’s harder for a gentleman to differentiate himself stylewise, so more and more men are turning to the bespoke shirt. Custom shirts can now be ordered from a host of makers: Ralph Lauren, Thomas Pink, even Brooks Brothers. Neiman Marcus has seen its custom-made shirt business increase so much over the past few years that it has created a special department, says Scott Fradin, vice president of men’s merchandising at the upscale department store chain.

But the Rolls-Royce of bespoke shirtmaking is Charvet. Founded in 1838, the Paris house quickly became tailor of choice for French aristocrats, and over the years it built a diverse international fan base that has included the Duke of Windsor, Yves Saint Laurent, John F. Kennedy, Vernon Jordan, and Vogue style giant André Leon Talley.

Charvet’s collection of 6,000 shirting fabrics is the largest in the world, and the consultants at its Place Vendôme flagship store—mere steps from the Ritz—will show bolt after bolt of the softest Sea Island cottons, Egyptian cotton broadcloths, royal Oxfords, and gabardines to the discerning customer. They have winter weight, they have summer weight, they have weights for those shoulder-season days when one feels too cold half the time and too warm the other half. Don’t even consider just walking in and asking for a white shirt and a blue one: There are 400 distinct whites and 200 blues to select from.

“Charvet is about the possibility of choices,” says Anne-Marie Colban, the soft-spoken co-owner of the House of Charvet. “We like to design each shirt based on the customer’s personality.” First-time purchases begin with a bit of sartorial chitchat. What kinds of suits do you like? Do you wear jeans? What colors do you favor? After an in-house tailor narrows down color and pattern choices, the measuring process begins. Charvet takes more than 25 measurements, which are then transferred to paper and reproduced in poplin format 10 days later. This prototype allows a customer to make any last-minute recommendations or adjustments. The finished shirt arrives at the owner’s doorstep in four weeks.

The experience is at least half of the appeal, according to 34-year-old Adam Zurofsky, a partner at the New York law firm Cahill Gordon & Reindell, who owns four Charvet shirts. “They are clearly trying to build a lifelong customer.”

At some point in the process, cost will need to be discussed and a platinum card handed over—prices range from approximately $430 to nearly $1,300. But this isn’t really the kind of shop for someone who will quibble over a euro (or a hundred, for that matter), and Charvet’s owners have found cost to be of little deterrent. “Men come here alone and get lost for hours, really,” says Colban with a laugh. “It’s a candy store for grown men.”

Of course, while there are buyers for champagne-filled truffles, there are even more for M&M’s, and Charvet has taken a pragmatic approach to the realities of the marketplace. The company also makes fine off-the-rack shirts—the ones sold in the U.S. are more generously cut than their European counterparts—which are available at Bergdorf Goodman, Saks Fifth Avenue, Neiman Marcus, and various boutiques, with prices starting at around $395. “The typical American customer starts with a Charvet white dress shirt—nothing too aggressive,” says Michael Macko, director of men’s fashion at Saks Fifth Avenue. “Before long, you have that same customer buying six shirts at a time. Sometimes they wipe out an entire size in our stock because they are buying so many at once.”

Charvet is also taking a gamble by extending its offerings beyond its traditional fit. Last year, it introduced a slimmer-fit shirt geared toward younger customers who desire something Charvet, but want to pair it with their low-rise jeans or urban-hip sneakers. The design sold quickly in France and Japan, and Colban believes it’s just a matter of time before it takes off in the States. But Charvet is unlikely to shed the traditional image and fit that have kept customers like Joe Marino loyal. “Its pattern and style have stayed consistent,” says the 27-year-old food and beverage consultant, who regularly attends Charvet trunk shows. “The Charvet brand is not diluted like other brands.”