Giambattista Valli, Designing for Women in the Know Valerio Mezzanotti for The New York Times Giambattista Valli at his studio in Paris. He has found success designing for European society women. IN the season between his last show for the house of Emanuel Ungaro in the fall of 2004, and the start of his own business in the spring of 2005, Giambattista Valli adopted a curious look that has since become one of his many signatures. On almost any occasion at which Mr. Valli, 45, appears, he wears a pearl necklace, usually contrasted against his thin frame, a fitted black sweatshirt and loose black jeans. It is hard to say whether the look is more Coco Chanel or Barbara Bush. Mr. Valli has worn the strand of natural pearls, which he said he purchased from a maharajah in India, ever since Luigi Scialanga, who does the jewelry for his shows, told him that "this is you, this is going to be your signature thing." Mr. Valli is all about a signature. "The hardest thing in fashion is not to be known for a logo, but to be known for a silhouette," Mr. Valli said recently in his headquarters, a fabulous building in Paris close to the Madeleine that happened to once have been the residence of another famous Italian of a similar given name, Jean-Baptiste Lully, a composer at the court of Louis XIV. Mr. Valli's store is on the street level; his atelier and couture salon are on the second and third floors, serving a court that includes multiple generations of Brandolinis, Dellals, Niarchoses and Missonis. Lee Radziwill is a regular at his fashion shows, even the ones he puts on for an additional collection he designs for the Italian outerwear company Moncler. Among a certain swath of European society, Mr. Valli is a sort of royalty, the only designer of his age group making unapologetically happy clothes, which speak to a French sensibility of upbeat party frocks. He is also the first designer in years to have a real breakthrough in couture, the rarefied and endangered business of ultra-expensive custom clothing. Some of his customers call themselves "Valli girls." But in the United States, Mr. Valli has only recently come into his own, perhaps best known for a one-off line that was briefly sold as part of a Macy's collaboration last year, or the occasional red carpet appearance, like Emma Stone's red dress at the Oscars this year. As Colleen Sherin, the senior fashion director of Saks Fifth Avenue and one of Mr. Valli's earliest supporters, noted: "A woman may feel a sense of discovery when she's buying one of his pieces. He's a designer for a woman who's in the know. Nevertheless, Ms. Stone's dress was slammed for its oversize bow at the neckline, which was as much a surprise to Mr. Valli as it was to viewers at home. "You bring your creativity, but there is a stylist who decides what she wants," he said. To put it another way, Mr. Valli can be a bit of an acquired taste, but he's quite a flavorful dish once you give him a try. In the seven years since he started his signature label, after working for the froth-specializing Ungaro label for seven years, he has created dresses that veer toward the froufrou. It was at Ungaro that Mr. Valli met the mothers - Andrea Dellal, Georgina Brandolini - and began to court their daughters, Charlotte and Alice, Bianca and Coco, well before they were the fashionable stars of haute Paris. In Mr. Valli's own words: "I have made bouquets of pleats, bouquets of flowers, bouquets of ruffles, bouquets of feathers. Often I design in mousseline, held tightly around the waist, and with something else going on all around. Some of his early, exuberant designs were derided by fashion critics, particularly American ones, as looking like hydrangea bushes, pepper mills or bathmats. While they were beautifully made, his designs once seemed distant from the work of his peers, but here's the thing: they sell. His gently gathered dresses, sold at Saks for around $3,000 apiece, have made Mr. Valli an important vendor for the store.