THE perfect Parisian woman is an illusion, bien sûr. But learning to pretend to be one is a serious business that dates back centuries.
It is an enterprise that continues to thrive with profitable how-to books like, “How to Become a Real Parisian,” “The Parisian Woman’s Guide to Style” and “All You Need to Be Impossibly French.” Now Inès de la Fressange, ex-runway model, former face of Chanel, Legion of Honor winner, designer, businesswoman and daughter of a marquis, offers yet another take on how to dress, shop, eat and act like a true “Parisienne.” This onetime muse of Karl Lagerfeld has spun her beauty and style tips into a confection of a best seller, “Parisian Chic: A Style Guide,” which has sold more than 100,000 copies in French and has just hit the American market.
The book might have withered and died on the shelves, except that Ms. de la Fressange combines a “je ne sais quoi” audacity with a sassy tone, and leaves readers believing that, by following her rules and experimenting with confidence, they, too, can be just like her.
They can’t.
Ms. de la Fressange is almost 6 feet tall, about 125 pounds and hipless. She has been the official model for Marianne, the ageless symbol of the French republic that appears on postage stamps and municipal buildings. She is wealthy and quadrilingual. She drinks wine and lots of strong espresso. She doesn’t diet. “Potatoes, chocolate, bonbons, wine, bread — I eat everything that’s good,” she said.
She is 53, but dared to pose topless for Madame Figaro magazine last year. “Photoshop helped,” she said, knowing you don’t really believe her. As for exercise, she said, “I thought about doing it once.”
She even smokes, a lot, but not in front of Americans. When asked about the three oversize ashtrays on the chrome and glass-topped table that serves as her desk, she replied: “You don’t see any ashtrays in my office! They are all art objects!”
She wears sensible lingerie from Etam and doesn’t use concealer to hide the circles under her deep-set eyes. One of her uniforms — a navy crew-neck sweater, rolled-up jeans and brown loafers — makes her look elegant-casual; most anyone else would look like the L. L. Bean catalog.
Ms. de la Fressange and Mr. Lagerfeld had a falling out decades ago but have since reconciled. After giving up modeling, Ms. de la Fressange became a fashion and accessories designer. Since 2003 she has been a “brand identity consultant” for Roger Vivier, the French shoe designer, installed in an office crammed with decades of her sentimental history in the Vivier boutique on the Rue du Faubourg Saint-Honoré.
She has just returned from Los Angeles, where she signed a contract to be one of the new faces for L’Oréal.
“I told them that France was an old country, and I guess they had to choose an old model,” she said: “They told me, ‘Oh, no, you aren’t the oldest. We had Jane Fonda.’ Facial bags are the new style!”
It is that blend of self-deprecation and irreverence, delivered in one-liners with deep, throaty laughter and a dramatic toss of the head, that both men and women find enticing.
      
“It’s the fantasy of the entire world of women, even French women, to be the perfect Parisienne,” said Bertrand de Saint-Vincent, the society columnist for Le Figaro and author of “Tout Paris,” a volume of essays on the Parisian glitterati, their style, their parties, their foibles. Asked who comes closest, Mr. Saint-Vincent does not hesitate. “Inès!” he said.
      
Despite her relaxed, flexible style, Ms. de la Fressange is a disciplined businesswoman who knows how to sell her brand: herself.
“She’s very clever because she knows the key to being beautiful is self-confidence,” said Sophie-Caroline de Margerie, a writer who captures the essence of Parisian style in “American Lady,” a new biography of Susan Mary Alsop, the American doyenne of French style. “In the end there’s no rule. It doesn’t matter what you wear, as long as it suits you, and as long as you feel pretty.”
      
Ms. de la Fressange is so strong a brand that the Galeries Lafayette department store is featuring this perfect Parisienne in a tie-in, with posters and advertisements of her in rolled-up jeans, black lace-up shoes, white socks and a beret, sitting behind an accordion. As for Ms. de la Fressange’s 239-page guidebook, it is printed with a leatherlike cover in shiny red with gold lettering. Ms. de la Fressange did the illustrations; her older daughter, Nine, who is 17, did the modeling. Its six-point guide to Parisian style includes a ban on coordinated outfits, feeling uncomfortable and looking rich.
Ms. de la Fressange also offers 10 lessons to master the “offbeat look à la Parisienne.” Among them: wearing jeans with gem-encrusted sandals, not sneakers; a pencil skirt with ballet flats, not heels; an evening dress with a straw handbag, not a gold clutch; a chiffon print dress with battered biker boots, not brand-new ballet flats; a sequined sweater with men’s trousers, not a skirt; a tuxedo jacket with sneakers, not femme fatale stilettos.
      
The perfect Parisienne never uses soap on her face or wears pink on her lips or goes out without makeup, even on weekends. She never buys long-stemmed flowers (too difficult to find a suitable vase), but likes to eat (“Rest assured, I do know a few size 4s.”). She washes her hair every morning. Asked if she feels like the perfect Parisienne, she replied, “Perfection is a nightmare. A great French wine would be nothing without the taste of the oak barrel or a touch of dust.”
      
Ms. de la Fressange’s life has not always been perfect. It turned tragic in 2006, when her husband, the Italian businessman Luigi d’Orso, died of a heart attack. She refers to the current love of her life, Denis Olivennes, a media executive, as her “fiancé,” even though they are not engaged. “ ‘Boyfriend’ sounds so childish, ‘partner’ sounds like a business. I guess I could call him, ‘the man I often see in the bedroom in the evening.’ ”
      
Then after all the lessons, and when you least expect it, she throws a curve. “Beware of good taste,” she commands in her book. “Who knew that black and navy were made for each other?” she writes. “No one — until Yves Saint Laurent gave us permission to boldly go where no one had gone before. You love orange dresses with yellow shoes? Go for it!”
      
Her book continues: “Fashion is constantly evolving, and that’s what makes it so interesting. The day will come when Parisians decree that mini-shorts with leopard-skin bomber jackets and studded ballet flats are the best things since sliced bread.”
But what true Parisienne eats sliced bread?