A breathless hush descended on the packed New York theatre, as two young women floated across the stage like heavenly beings. Dressed in diaphanous costumes, which cascaded in waterfalls of fabric from their sequinned headdresses to their sparkling shoes, the sylph-like figures moved in a symmetry so perfect it was almost unnerving. The audience was transfixed, hardly daring to blink, as the dancers pirouetted in front of an enormous mirror. Could this spectacle really be happening, or was it just a trick of the light? As the music faded and the dancers stepped into the spotlight to curtsy, the spell was finally broken by deafening applause.

When 18-year-old identical twins the Dolly Sisters danced onto the Broadway stage in 1911, they caused a sensation. Theatres swelled to bursting as people swarmed to see the girls who were a perfect mirror image of each other.

Once viewed, their thrilling double act was never forgotten. Dancers came and went during the early 20th century, but the twins' novelty appeal, combined with their exotic good looks, majestic costumes and faultless footwork, ensured they became international superstars.

To modern tastes, their most spectacular routines, like The Dollies and their Collies (in which they danced with performing pooches) and the Pony Trot (where they pranced around like sleek black fillies), sound kitsch, but audiences in 1920s Paris, London and New York were enthralled. And while the sisters briefly moved from stage to screen for The Million Dollar Dollies - which earned them plaudits and Hollywood friends like Rudolph Valentino and Charlie Chaplin - their live performances remained their crowning glory.

The Dolly Sisters created a stir off-stage, too. From Noël Coward to Tallulah Bankhead, everyone wanted to meet "The Heavenly Twins" - but it was their association with a succession of rich suitors that was most fascinating. Considered by some to be gold-diggers, legend has it the sisters would remove their jewellery when a wealthy man approached in the hope he'd take pity and furnish them with more. They took five husbands between them, but they were constantly pursued by male admirers, including a famous department store owner - who reputedly blew the bulk of his fortune bankrolling their extravagant lifestyle - and a future British monarch. Famous, too, for their love of casinos, they earned a reputation as the most inveterate gamblers in Europe, regularly winning - and losing - millions without batting an eyelid.

But for all the glitz and glamour, both women would know great heartache and tragedy. After retiring early from the stage, their luck changed. In a series of events worthy of an airport novel, the sisters endured crushing debt, business failure and broken marriages. And when one twin died in tragic circumstances, the other could not bear her loss. As one reviewer wrote: "Just as you could not see a man without his shadow, you could not conceive of how one of the Dolly Sisters could dance and live without the other."

Born to Julius and Margarethe Deutsch on October 25, 1892 in Budapest, Hungary, Yansci (Jenny) and Roszika (Rosie) were immediately issued with pink and blue ribbons to differentiate them. So perfect was their resemblance that when the ribbons slipped off, their mother couldn't be sure which daughter was which.

It was the girls' nursemaid who inspired their love of dancing with trips to the theatre and, before long, Jenny and Rosie were copying the dancers' routines during performances at home. By the age of eight, they were charging friends to watch them dance. Unimpressed, their father sent them to a convent school in Berlin, Germany, where the girls' high kicks and splits also failed to wow the nuns, and they were asked to leave.

When the twins were 12, a mysterious financial setback led to a family move to New York City, and the girls' education was shelved in favour of dancing lessons. They were fast learners and were soon appearing in small-town venues - at one, a choreographer pronounced them as cute as dolls, and so their stage name, The Dolly Sisters, was coined. Although young, Jenny and Rosie toured with vaudeville shows across the US and even went to Cuba, where they became known as "Las munecas Americanas" or "The Little American Dolls". At 15, they were performing in chorus lines on the New York stage, and a year later had made it into their first Broadway show, albeit in minor roles. But it was their appearance, at 18, in the famous Ziegfeld Follies, a spectacular show staged annually, that changed their fortunes. Creator Florenz Ziegfeld gave a rare downbeat assessment - "You can't do much, but you're cute" - but soon raised their salary from $90 to $350 a week.

Sublimely beautiful, with flawless skin and glossy brunette hair, Jenny and Rosie soon attracted attention for more than just their dance steps. One awestruck fan was 54-year-old millionaire financier "Diamond" Jim Brady, so-called because he wore diamonds from head to toe. Famed as much for his appetite as his wealth - one restaurateur said he was "the best 25 customers I ever had" - Brady adored escorting the sisters to the races and casinos, whetting their appetite for gambling. He also lavished them with jewellery and gifts, once buying them a Rolls-Royce. Rosie, though, insisted their relationship was strictly platonic. "He used to say that if we hadn't parents, he should have adopted both of us," she said.

Certainly, the sisters' own affections lay elsewhere and, on April 10, 1913, 20-year-old Rosie married Jean Schwartz, a songwriter 14 years her senior, and was followed down the aisle a year later by Jenny and comedian/singer Harry Fox. The happy couples rented adjoining apartments in Manhattan, and although the sisters wore different outfits so their husbands didn't confuse them, Schwartz apparently took no chances by having Rosie eat an onion each morning.

By now a formidable double act, the Dolly Sisters had also started performing separately, even though they found being away from each other "a horrible nightmare". The first time they were apart, with Rosie touring in Boston and Jenny in New York for a musical, they spent half the day on the phone to each other and the other half in tears. Reunited two months later, looking ill and gaunt, they vowed never to be apart for so long again. Individually, the sisters may have been brilliant, but together they were magical. Sharing the stage for another Ziegfeld production, Midnight Frolic, in 1916 and dressed in couture costumes, one critic gushed: "The sisters are dancing like slim sylphs ... their frocks are confections assembled by a genius ... altogether, the Dolly Sisters are adorable." Roles in 1918's The Million Dollar Dollies, a film written for them, followed, and hot on its success they were wooed to London in 1920, where one theatre impresario declared: "Two more electric personalities it has never been my fate to meet."

The rest of London seemed to agree, and the Dolly Sisters were soon embraced by the cream of society, counting millionaire tea magnate Sir Thomas Lipton and matinee idol Ivor Novello among their new friends. At one party, they were introduced to the young Prince of Wales, the future King Edward VIII, who seemed particularly taken with Jenny. "It is difficult to realise he's the idol of the world, he's so unassuming," she enthused, after being spun round the dancefloor by her royal admirer. In the years that followed, Jenny's path regularly crossed with that of the prince, fuelling gossip that their meetings in the hot spots of Europe were more than mere coincidence, although Jenny herself refused to be drawn on their "friendship". "If the Prince of Wales ever kissed the Dolly Sisters, they're not telling on him," wrote one exasperated reporter.

Less discreet were the sisters' forays into the casinos of the French Riviera, where they built up a reputation as fearless gamblers. It was a time of unadulterated excitement for the twins. Having left their marriages in the US behind, they embarked on a much more exciting lifestyle, flitting between New York, Paris and London for work engagements followed by late-night partying. Their one beauty secret was to never touch alcohol, and their stage routines - from ballet and waltzes to the foxtrot and jazz - were all they needed to stay in peak physical shape. As one reviewer observed: "Their arms and their legs are hard as steel, their muscles as firm and their figures as flexible as any athlete could desire."

Now truly international stars, the Dolly Sisters played to packed theatres, combining their precision routines with increasingly spectacular stage costumes. Booked for a series of Paris shows, such as Oh Les Belles Filles and Paris En Fleurs, Jenny and Rosie stunned audiences in velvet and lace frocks, flowing Grecian gowns, and frothy hats trimmed with osprey feathers, prompting the maxim that the Dolly Sisters were "worth the price of admission just to look at". They turned heads offstage, too, regularly arriving at parties dressed in luxurious outfits designed by French couturier Jean Patou. When Harry Gordon Selfridge, the millionaire owner of the famous London department store, met Jenny when she was 33 (he was almost 70), the businessman was instantly smitten - so much so that, despite the rejection of his marriage proposals, he romanced her for 10 years, frittering away millions and almost bankrupting himself in the process.

Both sisters benefited from Selfridge's generosity - he once bought them each a pet tortoise with rare blue diamonds set in their shells - but it was Jenny who had the most advantage from his wallet. At the casinos of the French Riviera, he'd sit behind her as she gambled the night away, chivalrously covering her losses while insisting she keep the winnings. He showered her with furs and jewellery, too. According to biographer Gary Chapman, in The Delectable Dollies (History Press, $49.95), on one occasion Jenny arrived at the baccarat table dressed in a chinchilla cape and covered in a riot of jewellery that caused one onlooker to exclaim: "My eyes popped. I had never seen so many jewels on any one person in my life. The magnificent necklace she wore around her neck must have cost a king's ransom."

While Jenny was enjoying the spoils of her relationship with Selfridge, Rosie, too, had her eye on the money, breaking off a two-year engagement to a Parisian businessman to marry Mortimer Davis Jr, heir to a vast tobacco fortune, in 1927. Described as "somewhat too fat", when Jenny remarked on her brother-in-law's excessive weight Rosie shot back: "Yes, but he's all pure gold." They separated a year later, but, happily for Rosie, the divorce settlement left her with a size-able proportion of Davis's inheritance.

The cash was to come in handy when, in December 1927, aged 35, the Dolly Sisters shocked fans by announcing their retirement. Earlier that year, Rosie had been critically ill with intestinal poisoning and appendicitis, and her brush with death seemed to change the aspirations of the sisters, who claimed they were giving up their careers to "settle down to a retired life far from casinos, cafes and bars". But the reality was a little different. Their obsession with gambling meant they never strayed far from the gaming tables, where their recklessness afforded them huge wins and colossal losses - in one night, Jenny lost tens of thousands of dollars, while Rosie scooped $US800,000.

In retirement, the twins began to lead separate lives. While Rosie married Irving Netcher, heir to a US department-store fortune, in 1932 and became a lady of leisure, Jenny - with Selfridge's help - bought a chateau near Paris and opened a couture shop on the Champs-Élysées. But while Rosie happily settled into her new life, Jenny seemed to be searching for something to fill the void her sister's absence had left. On a trip to Budapest in 1930, she adopted two five-year-old girls, Manzi and Klari, and, bizarrely, tried to pass them off as twins, saying they were going to be the new Dolly Sisters. Back in Paris, Jenny - with children in tow - continued to frequent the casinos with Selfridge. Meanwhile, Rosie gadded around the world with her new husband. For one of the twins, however, their privileged life was about to come to an end.

On the misty night of March 2, 1933, Jenny's chauffer-driven car was involved in a horrific crash near Bordeaux, leaving her life hanging by a thread. When she came out of a coma five days later, she was shocked to see her face smashed beyond recognition, and was forced to auction off her jewellery to pay for plastic surgery. After 15 painful operations, her beauty was mostly restored, but mentally, she never recovered. Shattered by the closure of her shop due to the effects of The Great Depression, and spiralling deeper into debt, Jenny received another blow when she was fined for failing to pay tax on her jewels. With Selfridge mired in his own financial crisis, an abortive second marriage to Chicago attorney Bernard Vinissky, and her sister nowhere in sight, for the first time in her life Jenny was broke and alone. Depressed and desolate, on June 1, 1941, aged 48, she hanged herself in a rented Hollywood apartment, while her children played on the beach.

Although she was devastated by her sister's suicide, Rosie was determined to carry on, in true showbiz style. She sold the rights to their life story for the making of the 1945 musical The Dolly Sisters - starring Betty Grable and June Haver - as a way of keeping her sister's name alive. When Rosie's husband died of a heart attack in 1953, the keen traveller continued her regular jaunts with a young gay male companion, but wherever she went, her twin was never far from her thoughts. Without her beloved sister, and trapped in an ailing body, she decided to end her life, taking an overdose of sleeping pills on April 20, 1962. But she survived, dying in Manhattan of a heart attack almost eight years later on February 1, 1970.

Not long before she died, Rosie told gathered friends: "It's been a beautiful life. Life has been grand to me and I thank God every day, every night, that He's given me a beautiful, wonderful life." Anyone who saw them sparkle so brightly onstage might have also thanked heaven for the Dolly Sisters.