At 3 a.m., in her expensively overdone pink boudoir, she looks and acts the role of accomplished femme fatale. Dropping her black net pantyhose on the wall-to-wall leopard carpet, she shrugs into a filmy French nightgown, curls up on the $12,000 queen-size bed and muses over her appointment book. "The good thing about my life," says Diane von Furstenberg, "is that one week I'm single and the next I'm not." As if to explain she dials a number in California on one of the five telephones in the master bedroom suite. "Hello," she coos to Barry Diller, chairman of the board of Paramount Pictures, "do you love me?" A photograph of Diller, the principal man in her life for the past three and a half years, hangs near the bed. "But there are others," she says. "That's important." Among them is California's Gov. Jerry Brown, whose picture is also hung there like a trophy. "He was the first governor who ever kissed me," she explains.

At 8 a.m. she is out of bed and into the shower, singing blithely off-key with Billy Joel. The telephone rings. It is her husband, calling from his nearby apartment. She chats briefly in French, then hangs up. Five minutes later, while rubbing lotion on her thighs, she calls him back. "Do you love me?" she asks.

They are legally separated, but she remains a warm friend of Prince Egon von und zu Fürstenberg, a German whose noble ancestry goes back to the 11 the century and whose wealth comes from his mother, an heiress of the Italian Fiat fortune. Despite such genealogical credentials, Diane has never qualified for the snooty Social Register of New York, her home for the last decade. As the daughter of a self-made Jewish millionaire and a mother who survived 14 months in Hitler's concentration camps, Diane learned the value of self-reliance and independence early on. "I will always get what I want," she told her mother at the age of 11. She has pretty much done so—as a stunning business success, among other ways. She is chairman and sole owner of Diane von Furstenberg, Ltd., a $150 million fashion empire that peddles ready-to-wear dresses and 19 other products ranging from cosmetics to wallpaper and table napery. She pays herself $250,000 a year in salary and commissions. In a world that caters to women but has long been dominated by men, she is the biggest name since Coco Chanel.

Von Furstenberg changes from kittenish siren to brisk businesswoman as quickly as she can slip into one of her own celebrated (size 8) wraparound frocks. When the conversation with her husband ends, she presses a button for a direct line to her office. "Hi. Anything?" she asks her secretary, Ellen Levinson. "Any news about Gimbels? Did you call them? Well, clear up Gimbels." She pushes another button and her maid enters silently with clothes for the day. Putting on a pink blouse and a black velvet skirt, she explains: "I'm wearing rejected samples." She sprays her Tatiana perfume (named for her 8-year-old daughter) on thighs and ankles, and steps into black, spike-heeled pumps. She picks up the phone again, summoning Diller's Manhattan chauffeur to drive her to the office. Cradling the phone on her shoulder, she applies her patented DVF rouge as she talks. "Hi. This is Miss von Furstenberg." She is never called Princess in the business world. "Do you think Mario could pick me up—like immediately?" Jamming her appointment book into a leather handbag, she strides to the door. "I gave my own driver a trip to Cuba as his birthday present," she explains. "He hadn't seen his mother for 20 years." In the limo she asks Mario for a stick of gum.

Breezing into her midtown office Diane is all crisp efficiency. No phase of the business escapes her. Still chewing gum, she inspects new mirrors for the showroom. "It looks nice, huh? I want the offices to look like an Esther Williams movie set." She has succeeded; her 17-room headquarters, like her apartment, are a foaming melange of reds, pinks and lavenders. Sitting at her desk, she intersperses telephone calls with orders to the staff. She discusses a forthcoming series of TV promotions and orders a print of the film Autumn Sonata for screening in the projection room of her country home. She considers her schedule: "Tomorrow? I'm going to Boston to get an honorary degree or something [at Babson College]. Friday I'm supposed to go to Hackensack. Ellen, find out what kind of audience. And maybe I should bring some perfume? Is someone going to Puritan to pick up a suit for me to wear tomorrow?" Puritan is the franchised distributor of her fashions to 2,000 department stores and boutiques.

In the design studio she kicks off her shoes and squats down to paw through a drawerful of prints, wallpaper and swatches of designs she has squirreled away as possible inspirations for her print dresses. "Nancy," she calls to one of the eight designers she employs, "take this print. Use plaid to coordinate with it. I'm just beginning the holiday line." She sighs. "It gets harder and harder."

Unlike Charlotte Ford, Gloria Vanderbilt and other social lionesses who have ventured into fashion, Diane is not content to dabble in design, act as front woman or settle for her signature on the hip pockets of jeans, leaving the business end to others. Her simple and sensationally popular wrap and shirtwaist dresses (at $80 and up) spelled the end of the pantsuit—and ultimately created a crisis in her own shop. "At one point we were producing 20,000 dresses a week to fill the demand," she remembers "That's 40,000 sleeves." By 1977 overproduction had dumped her dresses into the bargain basements. Drastic action was called for. "I had to save my reputation," she says. In the past year she restructured the business and took charge singlehanded. "I bought out my partners. I changed my lawyers. I changed my accountants. I changed everybody. For about a year I walked around with a big knot in my stomach, but I was determined to clean up the corporation and make it work." Richard Conrad, her original partner, who paid $250 for a 25 percent interest in the business in 1971 and sold it back for more than $1 million last year, denies there was a crisis of mismanagement. The cosmetics line and other von Furstenberg products more than made up for the drop in ready-to-wear, he insists. "The business was never in trouble. Diane just wanted total control."

Fluent in five languages as well as the glib jargon of the rag trade, von Furstenberg knows her way around the garment district lofts, the freezing customs sheds at Kennedy Airport and the grand salons of Paris. She calls everyone by his or her first name, although employees are addressed with a certain aloof noblesse oblige. With her company president, Shepard Zinovoy, she negotiates all the deals—the granting of franchises, the opening of boutiques, the consignment of orders—and understands the meaning of every bottom line.

At 32, she looks older than her years, but has a birth certificate to prove that she was born in Brussels on New Year's Eve 1946. Her father, Leon Halfin, General Electric's distributor for Belgium and Eastern Europe, doted on her. "He would give me anything, even if he could not afford it," she says, adding, "My family had money, but not"—she practically shouts the word—"MONEY." Egon disagrees: "She was like a rich girl from upper Scars-dale. She had designer dresses. At 15, I think, she got her first mink." "I never had a mink," Diane retorts. "Oh, maybe it was the ocelot when I was 19 or 20."

Her Greek-born mother, Lilly Nahmias, was sterner, upbraiding her daughter for her malicious teasing of younger brother Philippe. As a child in Brussels Diane "was proud. I didn't mix much. I only had one friend and we used to play princesses. We both grew up and married princes." The Halfins split up when Diane was 13, and she was packed off to schools in Spain, England and Switzerland before moving in with mother Lilly and her lover in a Geneva apartment.

When she was 18, she met Egon. "She turned me on," he recalls. "I thought he was silly," says Diane. But a year later they became lovers on her mother's rollaway bed. At 20, she went to work briefly for Bernard Gornfeld, the financial manipulator, and then served a short apprenticeship with Angelo Ferreti, the Italian fabric designer, where she learned about yarn, pigmentation and other tricks of her future trade. Meanwhile, Egon went off to New York in the employ of Chase Manhattan Bank. When Egon invited her to cross the Atlantic and move in with him, Diane accepted. "We needed each other," she says. "I loved him." They became engaged in spring 1969 and confirmed it with an emerald ring that Egon's mother, Clara Agnelli Nuvolette, had given him. Diane jokingly wondered if the engagement and the ring were fake. He soon left on a round-the-world trip, and when he got to Hong Kong a cable from his fiancée was waiting: "I'm pregnant. What should I do?" Egon gallantly cabled back: "Organize wedding July 16. I'll be back July 13." They were married in Paris at a $100,000 extravaganza staged by Leon Halfin. Egon's mother welcomed the match, but his father, Prince Tassilo, scorned her as beneath the family. Although he witnessed the ceremony, he refused to attend the reception. "Eddie [Egon] understood," said Tassilo later. "He sent a girl to my hotel room." Her father-in-law's disdain infuriated Diane. "It made me feel small," she says. "My life today is a reaction to that."

The von Furstenbergs (he was 23, she 22) settled into a Park Avenue apartment with the help of remittances from both families, and succeeded Carter and Amanda Burden as the darlings of international society, New York chapter. Their son, Alexandre, was born the next January, and within two months Diane was pregnant again. By then she was involved in the fashion scene, and when Tatiana was due she cajoled her doctor into delivering the infant 10 days early by cesarean section so she could get back to her job in time for the spring sales. Until she and Egon separated, in 1973, the children lived in a separate apartment with an Italian nanny; nowadays they live with their mother, and grandma Lilly spends eight months of the year with them in New York. Weekends Diane drives the family up to her 53-acre, 18th-century Connecticut home, where she does most of the cooking. The children are ambivalent about their mother's career. "Sometimes I mind her working," says Tatiana, "but sometimes I like it." "She's a little weird," adds Alex, "but she's a good businesswoman."

No one can contend otherwise. Just a decade ago she had three jersey dresses run up by a seamstress (she has never learned to sew herself) and took them around to Diana Vreeland, then the editor of Vogue. Vreeland advised von Furstenberg to rent a showroom at the Gotham Hotel, where many out-of-town buyers stay, and she ran a photograph of one of the dresses in the magazine. The response was astonishing. Diane thereupon hocked a $10,000 diamond ring, was given a $30,000 gift by her father and, as she had promised her mother years before, she got what she wanted.