Hidden cameras on the walls of the exclusive Wafi shopping mall in Dubai captured, in 2007, two Audi S8s smashing through its glass doors. The first – white with silver wheels – crashes through in reverse, while the second – a black car with a woman at the wheel – drives head on. The white car pauses briefly as a man in a black bodysuit and balaclava jumps out before the driver hits the gas again. You have to imagine the screeching of tyres as they speed on through the public atrium and reverse the car into the door of the Graff jewellery store.

The man in black runs into the shop and another joins him; both are carrying revolvers in one hand and small pickaxes in the other, and have pouches attached to their bodies. The store attendants run for their lives and the men calmly, systematically, start to break through display cases. At each one they seem to smash the glass and grab the jewels in one smooth move. You assume they have done this before.

While the security footage resembles a movie, really it's just a typical night's work for the Pink Panthers – the most successful diamond-thieving gang in history. At the last count they had committed 341 armed robberies and aggravated thefts around the world, with an estimated value of stolen goods of ¤330m. Their exploits have become the stuff of legend, with jobs ranging from London to Tokyo, Geneva to Singapore. The gang, a loosely affiliated network of an estimated 200 to 220 people, pull off jobs with precision and style, dressing as golfers for one job, Hawaiian tourists for another, workmen for one more. They can escape by speedboat, scooter or bicycle depending on the location, and take full advantage of soft borders and false documents. They know that as long as they get back home – to various Balkan countries – they will be safe, protected by either corrupt or hopeless officials.

The Dubai robbery was stunning for the amount they stole ($3.4m), the time it took (in 170 seconds they had left the store, jumped back in their cars and left the building), and the precision of their planning. The gang only drives Audis – you can't do a robbery driving a car you don't know; it's too risky. But Audi was a make virtually unknown in the Middle East in 2007 and getaway cars have to be found and stolen just hours before a robbery. The S8 is the brand's flagship high-performing car: so rare was the model in Dubai that one of the cars was stolen in the neighbouring emirate of Abu Dhabi and driven across the border.

The thieves reverse-rammed the car so the airbag wouldn't open on impact and so that the car was in the perfect position to drive away. They planned the timing of the heist (9pm) at the end of the rush hour, knowing that when they fled down the highway the lanes in the opposite direction – from where the police would come – would be jammed. They drove to a deserted, unlit patch of land between two mansions – just minutes away from the royal palace – and set fire to the two cars. In a now completely unknown third car, they drove calmly into the night with their multimillion-dollar booty.

So who are the Pink Panthers? I have been trying to answer that question for three years, since I first arrived in Belgrade to shoot a documentary on them. Armed with two phone numbers, I travelled down to Podgorica, the capital of Montenegro, to try to track them down. My contact had arranged various introductions, and I was told to go alone and with no mobile phone to a deserted war memorial on the outskirts of town. It was a good spot for a meeting: private, discreet, hidden by trees. As I waited, I realised it was also a good spot for a drug deal, a heist or a murder, which was when I got nervous. A beaten-up blue Peugeot estate pulled up alongside me.

"Please excuse my car," said a man in perfect English. "We like to travel quietly down here." This was Novak, a tall man in his 50s wearing white trousers, a pink polo shirt and a gold tooth. I got into the car and we drove to a local bar. He explained he was an alarms and electrics specialist for the Pink Panthers. He'd been looking forward to meeting me, he said; he loved journalism – he had been a local fixer for newspaper hacks during the wars of the 1990s. He smuggled reporters in, got them false documents and researched their stories. It was the perfect training ground for his current work: strategic thinking, adrenalin, cash, danger. And also, according to Novak, a moral high ground.

There are "no victims to what we do", Novak told me. "We scare people but we do not hurt them. We only take expensive things from rich people." It's the mythology the Pink Panthers try to promote, and he has a point: despite the fact that they terrify the life out of people working in the shop, until last year no one had been seriously injured in a Pink Panthers robbery.

Daylight robbers: (from left) suspects in the Dubai robbery Dusko Poznan, Bojana Mitic and Milan Ljepoja. Photograph: Observer

My meeting with NOVAK opens doors. A few weeks later I meet Mike at a bar on the coast in the height of summer: he is darkly tanned, in navy shorts and boat shoes. Apart from the scars on his arms, he would walk the Croisette well. He, too, is wearing a pink polo shirt. We joke: it's the equivalent of a carnation on a blind date.

"I don't have a badge that says Pink Panther on it," he chuckles. "It's nothing to do with us, this name. But I do like those films… Everyone in the Balkans knows The Pink Panther." It was the Daily Mail which named the gang after Peter Sellers's famous Inspector Clouseau film, after two thieves pulled off the largest jewel heist in British history at Graff, the Bond Street jewellers, in 2003. Within days Scotland Yard had identified a Montenegrin man living in Bayswater. When they raided his London flat they found, among other things, a blue diamond ring worth $750,000 in a tub of face cream.

Mike is a safe-cracker. He learned his trade while apprenticed as a teenager to a Kosovan criminal in Italy. "Mechanical, numerical, digital ones – I can crack them all. Digital safes are the easiest: you just dust them and see the fingerprints and you know everything. Numerical ones are the hardest: you have to have very good hearing and a very good memory." Mike is also very paranoid. This, he tells me, is "a hazard of the job". He pops Valium like aspirin.

The mainstream concept of a "mafia" is entirely informed by what we know of the Italian families – a strict hierarchy, a top dog, initiation ceremonies, and a lot of murder. The Pink Panthers are very different. "We are a network of teams working together," Mike tells me. "As soon as I got involved I became part of the network." The structure is likened by Interpol to al-Qaeda – the ultimate contemporary crime gang – in that it is a series of cells that come and go overnight, working independently. They share methods, they share contacts and they share origins, but it is to everyone's advantage that links are thin.

"There is an inner circle," explains Mike, "who have been doing this a long time, and we call each other family, but there are guys who don't know who their bosses or associates are. You have to be with them a long time dealing with the bigger jobs. You get tips from your supervisor – but there is also a wider chain of people. You don't know where you stand in the hierarchy because you never meet the 'boss'. There is no 'Big Boss'.Everyone has their specific job to do, so we all depend on each other."

You can't visit the Balkans without recent history looming large. Many, many people are still furious or bitter or heartbroken, scarred by the vicious, terrible wars. Buildings in Belgrade are still bombed out. Factories lie empty, crumbling as poverty-stricken townsfolk remember the golden days of Yugoslavia. The people who aren't angry are the ones who either got away or made money from that period. The Panthers did both.

Mike was a classic example. A boy and teenager under Tito, he grew up in a communist dream: enough to eat, a great education, an excellent athlete and proud of his glorious nation. But after the death of Tito in 1980 Yugoslavia began to fall. Republics began to compete, and a very nasty nationalism became the political weapon of choice.

"I was ethnically Albanian, but living in Serbia," says Mike. "The hatred became visible. Just pure hatred. Everything was cracking open."

To catch a thief: filmmaker Havana Marking in the CCTV room at the Wafi Mall in Dubai. Photograph: Observer

As Yugoslavia collapsed around them, the fate of the nation became apparent: conflict, militias and a total criminalisation of the state.

It was the 1992 UN sanctions against Yugoslavia that really determined the fate of the Pink Panthers. Entire industries in Serbia collapsed, creating a generation of people either forced or willing to take part in criminal activities. Once you have to smuggle food, soap or diesel to make life possible, what's to stop you smuggling arms, drugs and people to make life profitable? It paved the way for the hugely powerful international heroin, sex and gun gangs that still trade today: the small and mostly localised smuggling routes over the mountains, across lakes and between bays became international pathways. A few years later, diamonds joined the routes.

I asked people I met in the region what they thought of the gang. And while almost everyone acknowledged that stealing was wrong, the statement was usually followed by a glint in the eye and a sentiment along the lines of: "You have to admit they are good at it."

One man in a marketplace became passionate: "If I was the government, I would encourage the Panthers to go and hit all the foreign jewellers, under one condition: that they bring the booty home!" He saw the robberies as revenge for the Nato bombings and UN sanctions of Serbia in the 1990s – "England, America, France, Japan… they ruined this country."

I had asked Mike about women in the gang. They are usually hardly mentioned in the reports of the robberies. I had been told by Interpol officers in Belgrade that they were mere eye candy, irrelevant to the actual job. On the contrary, Mike said. "Women in the Panthers have to be exceptional. We have high requirements of them because they have the leading roles, but you can only have one in each gang. She has to be intelligent. She has to be beautiful. And she has to love money very much…"

And so Mike introduces me to Lela, a past associate and friend of his. She is extremely pretty, in her 40s and dressed in black from head to toe, with a lot of leather and fur. "Not anyone can do this job," says Lela. "You must be born to do it. The guys do the majority of the job, but they need a woman on their team. Without a woman nothing could be done."

Lela's job was to scout the target shops before a job. She would enter in the guise of a customer and furtively examine everything she could. On leaving, she would meet with an artist who would sketch the plan of the shop – down to the nearest centimetre. "If I made a mistake, they would be doomed." The surveillance could take months, not to mention a lot of money. "She had to be dressed in the most expensive clothes and elegant jewellery," says Mike. "She had to have her own chauffeur. She had to be like Madonna!"

It also required frequent "transformations" for her multiple identities: "Hairdressers would come to my house," recalls Lela. "I'd be sometimes blonde, sometimes brunette, redhead."

Sounds glamorous, I say.

"No," she shoots back, "I hated it! I felt like I would lose my identity. Like a doll who was experimented on."

Maybe it's because she's been unable to tell her friends and family about her work, but our conversation is beginning to feel like a therapy session. She tells me that she later had a nervous breakdown.

For Mike and his team, once they have stolen the diamonds, their job is done. The selling and carrying of diamonds is too risky: you have to pass them immediately to a prearranged contact, who will take them across borders to buyers, often in Antwerp. They know who in advance will buy what and for how much. The Pink Panthers receive around 15% of the value, the courier 5%.

Then there's the fence, the man who disguises the diamond, "legalises" it and resells it back into the market. Mr Green, a Bosnian Serb, is a very small man, with none of the swagger of the previous crooks I have met. He is fed up with the Panthers getting the glory. "They just do the street work," he tells me. "Without people like me they'd be nothing." He estimates that he receives 30-40% of the diamond's market value.

Mr Green tells me that he grew up a peasant woodcutter and joined the JSO, an elite Serb paramilitary unit. Led by Arkan, a notorious henchman of Slobodan Milosevic, the militia was feared across the region. He shows me his maroon beret with pride and I start to feel uncomfortable.

"I wasn't on the frontline," he says, "I was more in the background." This does not mean a back-office job. He was, he explains, "responsible for the liquidations of the terrorists". He seems unrepentant about his murderous past. He is the most frightening man I have met.

Everyone who was in the special forces has "business contacts", he explains. Those contacts stretched to West Africa, the home of many diamond mines, and to Antwerp, where Mr Green later set up a diamond business. His team re-cut the diamonds and create new certificates of origin, stating that each stolen diamond was mined in Sierra Leone recently. The diamond is usually untraceable. The Kimberley Process Certification System was set up in an attempt to stop the blood diamond trade. "In the end it just made it easier for us: we simply forge those certificates of origin and create a 'new' diamond."

The diamonds of very high value will usually make it back into the legal trade "on the hands of brides", he tells me, but the smaller ones have become the currency of the global black market. "You can have a pocketful of diamonds and buy a boatful of cocaine. Now any cash payment over ¤15,000 has to be traced electronically – but who controls diamonds? No one."

Mr Green is right about one thing: the Panthers do get the press. They drive like stunt men. Their robberies resemble movies. But they also get the heat, leaving the big money and the wider criminal networks untouched.

The Pink Panthers' crime spree in its current guise of hit and runs took off in 2000, then taking full advantage of the new systems in the diamond trade. And while they could exploit the soft borders of Europe and their own countries' corruption, the Panthers seemed untouchable for a while. It was only when various European police forces, notably in Monaco, Switzerland and France, connected that the Panthers were first thwarted.

In 2007 Interpol created the Pink Panther Working Group. For the first time global police forces were able to share and spread their information. The spectacular Dubai robbery of 2007 was one of their first successful cases. The Wafi Mall heist would have been perfect, but for one mistake: when they burned the getaway cars someone forgot to open a window. No oxygen means the fire can't rage as it should and so Dubai police managed to retrieve a good deal of DNA evidence. With the help of Interpol the DNA was traced to Dusko Poznan, a 30-year-old Bosnian and Milan Lepoja, from Montenegro. Both were wanted for heists in Switzerland and Liechtenstein.

In 2008 Poznan was caught after a car crash in Monaco, and Ljepoja after a dramatic police chase on the borders of France and Switzerland. Both are now serving sentences in Liechtenstein and awaiting trial for the Wafi Mall heist. The woman who drove the second car is still at large.

The unusual level of cooperation from the police forces, which has coincided with a political period of cooperation from the Balkans itself, has begun to have an impact. Since 2007, 189 Panthers have been arrested – 59 were caught last year. With Montenegro and Serbia keen to join the EU, it's no longer safe back home.

"It's much more dangerous," says Mike. "The police know all the tricks. We live much quieter lives now." Mike and Lela have both retired. When I went to find Novak again, he had been arrested.

And as the more experienced thieves cut their losses and return to the quiet life, police have identified a new generation of thieves taking over. They have none of precision or care associated with the older Panthers. Detective Inspector Jan Glassey of the Swiss Police Intelligence showed me CCTV from a recent robbery in Geneva. The thieves enter with much more violence, they don't have bags, they drop things, they panic and leave their gun on a table. "It is then that accidents happen," explains Glassey. "That is much more worrying for us."

Indeed the Pink Panthers have now had their first shooting: a policeman was wounded during a chase in Greece last year. Two men and a woman had been surveilling the jewellery store they planned to rob, but the wigs they were wearing aroused the suspicion of a police patrol, who stopped them for questioning. They fled the scene, shooting and injuring an officer, and all three were later caught (although the female accomplice – who turned out to be a former national basketball player – managed to break out of prison and is still on the run).

You wonder what Mike and Lela would make of it – getting found out because your wigs aren't convincing enough. The fact that the thieves were not even caught on the job, but a mere recce, suggests that standards are slipping. But as long as Mr Green and his associates are able to pass stolen diamonds off as new, there will remain a currency in demand throughout the criminal world. And somehow, somewhere, people will be trying to get their hands on them.

Smash & Grab: The Story of the Pink Panthers will be on released from 27 September at cinemas, on DVD, on BBC4 and BBC iPlayer. For more details see facebook/smashandgrabthemovie