“I notice only the ugliness in something,” the Milanese couturier Mila Schön said. “Take that away and it becomes beautiful.” Elegance and sobriety were perhaps better descriptions of her pared-down tailoring, which nonetheless for 50 years flattered with its graceful lines clients such as Jacqueline Kennedy and Farah Diba, the wife of the Shah of Iran.

Schön never became a star of the first rank in the fashion firmament, for her skills were perhaps better appreciated by cognoscenti than by the public. Yet she was the first Italian designer to brave the Japanese market, and among the earliest to show in America, where she was much esteemed. In 1966, at Truman Capote’s celebrated Black-and-White Ball, perhaps the last great couture event of its kind, a panel voted Marella Agnelli, the wife of the Fiat tycoon Gianni, the best-dressed guest, while the actress and socialite Lee Radziwill was third. Both were wearing creations by Schön.

Schön was unusual in high fashion in having no training in dressmaking. Instead, she had come to it as a client when, as the young wife of a wealthy gem dealer, she had travelled regularly from Italy to Paris to be fitted for clothes. She admired particularly the austere cutting of Balenciaga, and had watched carefully as her coats and dresses were made.

When she separated from her husband in the mid-1950s, she wanted to be able to give herself and her son the way of life to which she was accustomed. So with her mother she opened a small atelier in Milan. With the help of experienced seamstresses she began to make clothes for friends. At first these were essentially copies of her own dresses by Dior or Schiaparelli, but her good taste, eye for colour and appetite for work soon led her to develop her own style.

The signature of this was her use of double-faced textiles, pairing two kinds of wool or wool and cotton instead of having a conventional lining. She also revived the seldom seen palette of muted colours, such as brown and violet. In 1965 she was invited by the Marchese Giorgini, who had started the first Italian catwalk shows, to exhibit in Florence, and her collection of 25 dresses in different shades of violet made her name. The next year she opened a boutique in the Via Montenapoleone, Milan’s premier shopping street.

Her rise coincided with Italy’s economic boom, and the start of the country’s usurpation of France’s dominance of fashion. Schön’s clients included Italian celebrities and fixtures in the headlines such as Ira von Fürstenberg, and later Imelda Marcos. In 1969 she was invited to design the uniforms for Alitalia, and three years after that for Iran Air.

Her clothes largely shied away from ornamentation and from the splashy vulgarity that became associated with Italian designers. Instead, Schön derived much of her inspiration from the rigour of modern art, of which she was a collector. Klimt’s shimmering paint effects were transformed into layers of colour, while Lucio Fontana’s cuts and Calder’s mobiles provided line and movement. Other collections drew on Gobelin motifs, Persian miniatures and the textiles of William Morris.

She was born Maria Carmen Nutrizio in the Dalmatian city of Trogir, now in Croatia, in 1919. Her parents were wealthy landowners descended from the nobility, but in the aftermath of the break-up of the Austro-Hungarian empire they moved to Italy when Mila was still an infant. She grew up in Trieste and later in Genoa, where her father had been reduced to running a chemist’s shop.

In 1940 she settled in Milan. During the war years, she met and married an Austrian, Aurelio Schön, with whom she had a son, but his jewellery business then fell into difficulties and after 12 years together they were divorced.

In the early 1970s Schön started lines for men, women’s ready-to-wear, and diversified into accessories such as sunglasses and scarves. Later came a perfume and swimwear. By the mid-1980s she was in semi-retirement, but the business began to lose its shine and in 1993 she sold it to a Japanese firm, Itochu. A design team was brought in from the Krizia fashion firm, and with Schön once more playing an active role in the company it was able to open new shops in Asia and Russia.

This persuaded the designer Mariella Burani to license the name for several years. It was sold again last year to Brand Extension, a firm comprised of Itochu and the La Quinta group.

Schön died at her vineyard near Alessandria, in the Piedmont. A retrospective of her work, celebrating her half century in fashion, is due to open later this month in Milan.

Her son survives her.

Mila Schön, fashion designer, was born in 1919. She died on September 4, 2008, aged 89