The phone rings and she gets up from the grey, slab-shaped sofa and wends her way through the cluster of stylish but uncomfortable-looking leather and gold chairs towards the far side of the room.

"But that night I did say that - 'I will give you a son,'" she says, stopping at the edge of her desk to pick up the receiver. She puts her hand over the speaker. "But I think it was more of a sexual thing. Hello? Hello? Yes, I'm very well." She is speaking into the phone now. "I'm very good today. No. I was not OK yesterday, but I'm very good today and I'm very clear and I was excellent." The person on the line puts her on speaker phone. "Hi, guys," she says. She greets her grandson. Then she says, "I am going back to the boat on, er, Thursday. Then you all come, for the fashion show? OK. I love you. Bye." She hangs up.

"That was my son," she says. "As we were talking about conceiving him."

She walks back to the sofa. "It was more of a sexual thing," she says. "But it happened."

A lot of things have happened in the life of Diane von Furstenberg, 68. Her memoir contains Hollywood stars, European royals, tycoons, bohemians and one gorgeous Brazilian beach bum. The heroine is a beautiful woman from Belgium, born to a Holocaust survivor so emaciated that doctors had advised an abortion. Her birth is accounted a miracle.

Twenty-three years later, she arrives in New York, pregnant and bearing a suitcase stuffed with sample dresses. She finds fame as the creator of the wrap dress. She makes a fortune, loses it and makes another. Hollywood mogul Barry Diller showers her with diamonds; she leaves him for the Brazilian beach bum, who smells of frangipani flowers and clove-scented cigarettes.

Years later, after many passionate affairs with some of the great lovers of the age, the mogul and the ex-princess are reunited. He gives her more diamonds; he builds a fabulous house for them in California, to add to their collection of fabulous houses, and a yacht that is named after the Greek goddess of the dawn.

I visit the court of von Furstenberg towards the end of a hot summer's day in New York, stepping off the steaming paving stones of West 14th Street into a bright white lobby.

Portraits of von Furstenberg by Andy Warhol and Francesco Clemente look down from the high white walls, and a wide, white staircase, framed on each side by a curtain of wire-strung crystals, slices up through six storeys to the building's glass roof. Von Furstenberg, of course, always takes the stairs, like a mountaineer.

Beside her office is a yoga studio in which she stretches several times a week, and her living quarters: a glass penthouse set atop the building like a giant diamond. It contains a free-standing bathtub, made of teak, which reminds her of her time in Bali, Indonesia, with the aforementioned Brazilian. From her bed she can see the Empire State Building. There she sleeps alone - her husband, Diller, stays in his apartment at The Carlyle Hotel on weeknights.

When I enter her office she is behind a wooden desk of Viking proportions. I sit down on one of the uncomfortable-looking chairs, but she directs me to join her on the sofa. The back of it is low, so I perch on the edge while she drapes herself expertly across it. Her wide cheekbones are tanned and her auburn hair is slightly frizzy. This is apparently an indicator of her self-esteem - during her bleak years, she straightened it and when her confidence returned so did the curls. She is wearing a black and white check gingham shirt, black printed leggings and leather boots. She is skinny and lithe: at one point, she stretches her left leg through the air between us, pointing her toe, absentmindedly, and then retracting her foot again. She is fabulously sexy - definitely the most stylish woman of a certain age I have met.

What did I make of her memoir, she asks.

I tell her it made me jealous. I, too, would like to become a fashion icon and float around the world in a yacht. I feel I have not lived, I say.

"OK, so you can start," she replies.

The memoir is called , which I took to be a reference to the fact that so many women say they want to be like her. ("I want to grow up to be you," Kate Moss said when they met, apparently.) Von Furstenberg shakes her head. "It's something that I have said, so many times, without paying attention," she says. "When I was growing up, I did not know what I wanted to do, but I knew the woman I wanted to be."

She loved reading, and it was suggested that she might become a librarian. But "the librarian in my school had bad breath and thick glasses and I didn't want to be her", she says. "Then one day I was having dinner with Oprah … and she said, 'Oh my God, that's great, ' .' And I thought, 'Well, if Oprah thinks it's so great …'" Von Furstenberg felt she was "lucky to become the woman I wanted to be very, very early in my 20s".

Her father was affectionate - she credits him with making her confident around men. He met von Furstenberg's mother early in the war, but while he escaped to Switzerland, she was captured in 1944 while working for the Belgian resistance. To avoid betraying secrets or comrades, von Furstenberg writes, her mother claimed she was hiding at a safe house of the resistance because she was Jewish. The interrogator advised her not to say so; her mother ignored this and was deported to Auschwitz concentration camp. In a scribbled note, apparently dropped from the back of the truck that carried her away, she told her parents: "I want you to know that I am leaving with a smile."

Entering Auschwitz, the prisoners were divided. Her mother had fallen in with an old woman and stuck with her, but an officer in a white coat yanked her away and thrust her into the second group.

Her mother believed the officer was Josef Mengele, the so-called Angel of Death. At the time she was furious, yet his intervention saved her from the gas chamber. She often told her daughter this story. The moral was: things that seem dreadful may turn out for the best.

Von Furstenberg says her mother did not talk much about Auschwitz. Recently, the children of other survivors have begun contacting her; she is planning a dinner for them.

"Either [their parents] were very bitter and they made it very weighty on their children, or they didn't and it made the children very independent," she says.

And your mother did not?

"No," she says. "You know, I married a German prince. And my mother never said anything about that."

She was also never "allowed to have hang-ups", she says. It is, for instance, striking how candidly von Furstenberg talks about sex.

"I was young between the pill and Aids," she says. "My poor children, and you. Aids happened and it changed for ever the way we think about sex."

Von Furstenberg says things you hardly ever hear now from a famous woman. She talks about picking up men.

"I slept with a lot of people," she declares, proudly. "And I'm glad I did."

She writes, fondly, of losing her virginity at the age of 16, to an Iranian architecture student named Sohrab in a large damp room on Banbury Road, in Oxford, England. She was invited to address the University of Oxford's union recently, and went to find her lover's old flat, and the boarding school she attended, which is now the outpost of an Iranian university.

From a very young age, von Furstenberg says, "I realised that I had to have a relationship with me. I hate to be needy. That doesn't mean that sometimes I'm not, but I really fight it because I think it's very unattractive."

Each teenaged fling was a fresh adventure; her friend, interior designer Olivier Gelbsmann, "consoled each of my boyfriends when I left them", she writes.

If I were that person, I say, I might assume that we would get together eventually.

"Well, first of all, he's gay," she says.

Can straight men and women be friends like that?

"Yes, and also old lovers become great friends," she replies. "Because when you've had intimacy with someone, it's nice to feel a different closeness."

She met Egon in Geneva: driving out one day into the mountains, his car broke down. When a mechanic arrived, it started immediately.

"I remember Egon's embarrassed face," she writes. "It was his helplessness that seduced me."

Von Furstenberg tells me, "The men I've had in my life are very, very, very different. The one thing they have in common is they're shy. I find men's reservedness and shyness attractive. I am not very attracted to the joyful lawyer who tells jokes and plays golf. That's not exactly someone who would seduce me."

I'm afraid at this point I fall slightly in love with von Furstenberg and any rigour I might have hoped for as an interviewer falls away, like a wrap dress onto a bedroom floor. "Wow," I keep saying, in response to her various pronouncements. "That's amazing."

Before she married Egon and moved to New York, von Furstenberg served a sort of apprenticeship in the factories of an Italian fashion tycoon named Angelo Ferretti. He introduced her to jersey fabrics - knitted silk, or rayon, or cotton, or acrylic - which make wearable, form-fitting dresses.

"Christian Lacroix once told me, 'Women designers make clothes, male designers make costumes,'" she says. "There's something to that … Male designers hate jersey fabric because it doesn't look as beautiful, but women just love it because it's so much more comfortable."

Her wrap dress proved the perfect outfit for the sexual revolution, as it slips off so easily.

"I didn't think I was going to make a fashion impact and least of all did I think I was going to make a social impact," she says. But once the wagon was rolling, she did not spare the horses. "What's a pretty young girl like you doing reading ," a businessman asked her on a flight to Cleveland, in the United States, failing to notice that von Furstenberg, and her burgeoning empire, were the subject of the article on the front page.

Her sudden fame was "never good for Egon", she says. "I mean my success was so big and I was so young, and I think it was tough for him. But then he had other issues. He was very promiscuous."

They separated. In the years that followed, von Furstenberg would seem the living embodiment of the woman who has it all. By day, she was raising two children and a brand; by night, she partied at New York nightclub Studio 54.

"There was a parking lot right next to it," says von Furstenberg. She would park her Mercedes and step inside, in her cowboy boots. "I felt like a cowboy walking into a saloon. They would give me a beer … That was like: 'Yeah, I am the woman I want to be. I can have a man's life in a woman's body.'" She is not talking about gender per se. "No, it's that I didn't want to go: 'Oh, if I sleep with him, is he going to call me after?' Let him worry if I called him after."

"Wow," I say. "Amazing."

"It was the feeling of freedom, the freedom of pick-up. It was a great pick-up place."

Diller "exploded into my life" when von Furstenberg was 28 and he was the young chairman of Paramount Pictures. They met at a party she threw in New York; she was in Paris, France, when he invited her to Los Angeles for the weekend. She flew via Canada, ducking into a phone booth in Montreal airport to break the news to the Italian broadcaster who was then her lover. As the plane passed over Arizona, she adjourned to the bathroom and changed into a pin-striped suit and platform boots. He drove her away in his E-type Jaguar; another car followed with her luggage, to a mansion in Coldwater Canyon.

That night, "We were both very nervous, lying frozen in bed under the blanket," she writes. "We each took a Valium and went to sleep." The next day, after a very tense lunch by the pool, "we finally succumbed … and from the first moment our bodies met, he surrendered to me in a way that no one had done before."

It's a striking scene, I say. Two tycoons, both at the top of your respective trees, and yet … "Yeah, but that doesn't mean," she says, and breaks off. "My granddaughter teases me. She says, 'DD, you don't have any filters. You say everything.' I say, 'Right, I do.' And then I realise that I believe in God, but I don't really practise a religion. I think that what I do practise is truth. I practise truth. It requires a lot of practising, because it doesn't come naturally."

I say there are some things I would be too embarrassed to put in a memoir.

"You know, the truth is, you only regret the things you don't do," she replies. While with Diller, for instance, she had a brief affair with American actor Richard Gere.

"Hard not to," she writes, as if Gere were the last crumpet on a plate at teatime. I ask her about him and she dismisses the topic with a flick of her head. "He was boring," she says. "But you know, there was a time when I was young that I needed to be a huntress. I'm just so glad I was like that."

Her first relationship with Diller came to an end in 1980. Her mother had been admitted to a mental institution in Switzerland where she seemed to be reliving the horrors of Auschwitz.

"That, to me, was the most shocking," von Furstenberg says. "I'd never walked into a mental institution … The voice level is different. They all speak kind of higher."

After three weeks, quite miraculously, her mother "just snapped out of it", but it hit von Furstenberg hard. Seeking some perspective, she decamped, with her children, to Bali. There she met the Brazilian beach dweller, a chap named Paolo, who lived in a bamboo house "and hadn't worn shoes in 10 years". She brought him back with her to New York, presenting him at a dinner she gave for the editor of in her apartment on Fifth Avenue, like one of those Elizabethan explorers offering up a native dragged back from a far-flung shore. She was in love, not so much with Paolo, as with "the disruption that love can cause", she writes.

She was in love with the drama of it all?

"The drama, or the fantasy," she says. "But this all seems so long ago."

She would forsake Paolo and the fashion industry and take up with an Italian writer in Paris, founding her own publishing house and literary salon. In the 1990s, she would return to revive her dormant brand and to get back together with Diller. When they married at New York City Hall, in 2001, a reporter asked about the widespread assumption that theirs was a platonic relationship. She replied, tersely, that it was "very intimate".

Is this why she wrote in such detail about their relationship? To prove a point?

"Oh, no," she says. "I mean, Barry was many things. He was my lover first, he was my friend after and then he became my husband."

I suppose it seemed strange to people - the idea that you could be apart and have all these other relationships.

"It was meant to be," she says. "We've known each other 40 years this year. I'm glad we had this very passionate moment, but then I'm glad we haven't been together for 40 years … I'm happy that I had these other relationships. Then I ended up being with him.

"To some degree, we always thought maybe we would, you know. But listen … relationships are very personal and difficult to explain."

Von Furstenberg, meanwhile, is busy planning for the hereafter. She regards her brand, DVF, as akin to a third child.

"As a matter of fact, my son refers to my brand as 'my sister'," she says.

Her latest product is a bag called the Secret Agent, which ingeniously divides, like a space shuttle: a smaller leather capsule detaches from the main vessel. A woman can leave the bag in the cloakroom of a latter-day Studio 54 and proceed into the club bearing the clutch.

On her television show, she tutors 20-somethings to be "ambassadors" for the house of DVF. She has hired a new chief executive to run the business.

"I will slowly pull back from the operational side of my business and focus more on a bigger platform," she says. "My work with women."

She has constructed a cemetery, in which she hopes to be buried.

"Every day of my life I think about death," she says. "Every day."

She draws the cemetery for me on my notepad: two semi-circular stone walls, not quite touching. It is set in the side of a hill at Cloudwalk, her house in Connecticut.

Is there just room for one?

"No," she says. Apparently, it will sleep 35.

"Amazing," I say.

"Of course, you realise that if you do something like that, you could die in a plane and they'll never find your pieces. But people will come and mourn me there."

The Times Magazine/News Syndication