Denim jeans pioneer Renzo Rosso, the man behind the hugely successful Diesel label, first visited China 20 years ago and was staggered to find very few people were dressed in the Western world's most enduringly popular staple - casual clothing.

He vowed then and there to keep a close eye on the country and, when the time was right, introduce Diesel jeans to the market.

The Italian entrepreneur was spot on in his thinking - the company now has 32 stores throughout the country and plans to triple the number within the next five years.

"The spending here in China is much higher," Rosso says, speaking on the most recent of his regular visits to Beijing. "In the United States and Europe, consumers might spend $250 in the store; here it is close to $500. People buy more. It is incredible.

"Now China is becoming one of the most important areas for luxury brands. Europe is stale but China and Russia are doing very well."

In the early 1980s, Rosso became convinced that blue jeans would benefit from a major stylistic revamp, so he offered them in different cuts and in a "distressed" state, where the jeans were deliberately made to look faded, worn and even torn. The jeans looked secondhand, but Diesel charged much more than other premium brands, arguing that the denim used was of a higher quality.

Diesel was perceived as a cool, trendy and rebellious brand, and the clothes flew off boutique shelves.

The boss himself played the rebel role to perfection, dressing like a rock star, sporting tattoos and never being guilty of being the first to leave a party.

Nor has Rosso ever been accused of being self-effacing. He is proud of starting from scratch, even writing a book about how risk-taking and going against conventional wisdom built up a personal wealth that Forbes magazine recently estimated at $3 billion.

Forbes magazine says "he presides over a fashion empire that has made the farmer's son a billionaire".

"I was always a pioneer and people don't always understand," he says. "They thought I was stupid, so I brought out a book called Be Stupid, which explained just how crazy I was - 18 chapters of my life.

"We also did a campaign which was based around the theme of stupid. The book was very successful and people said it really energized and inspired them."

The Rosso empire now involves peddling far more than just blue jeans. Parent company Only the Brave - the motto emblazoned on Diesel products - now has majority stakes in other upscale fashion brands, including Maison Martin Margiela, Viktor & Rolf and Marni. Total group revenues are now to $2 billion annually.

Suzy Menkes, the respected fashion writer for the International Herald Tribune, says of Rosso: "For 25 years he has been a fashion innovator."

Despite the carefully cultivated bohemian look, Rosso has a sharp business brain that is well attuned to changing trends. Ideas, he says, can come from anywhere - at a bar, in the street, at a disco or at the movies.

Rosso says he is now looking at "expanding to watches and home furnishings".

Diesel's rapid growth means that Rosso is likely to be visiting China more often. The nature of his job means a constant shuttling across the world to check on the 400 stores.