RIO DE JANEIRO (AP) – Brazil’s well-heeled socialites swear by them. Legions of slum-dwellers from the country’s hillside “favelas” don them almost every day. Minimum wage earners behind juice bar counters use them, as do newly minted millionaires and, alarmingly, construction workers.

In Brazil, literally everyone wears Havaianas, the now world-famous brand of rubber and plastic flip-flops that’s celebrating its 50th birthday this year.

Since their 1962 introduction, Havaianas have joined soccer and samba as one of the great social equalizers in this country, among the world’s most stratified societies.

Initially the workaday staples of the Brazilian poor, Havaianas have transcended both their modest origins and the country’s borders to become an object of desire the world over, sold at Bloomingdale’s and Neiman Marcus and coveted by Hollywood A-listers, European royals and suburban princesses from Seattle to Seoul.

Not only have they become all but de rigeur in poolside Miami and beachfront Cancun, Havaianas now have a way of cropping up where you least expect them, from Paris’ rarified haute couture catwalks to the red carpet at the Oscars.

The iconic flip-flops now rival uber-model Gisele Bundchen for the title of Brazil’s most famous export. And though the word “havaianas” means Hawaiian in Portuguese, the flip-flops have come to be something of a symbol for Brazil itself.

“They’re cool, colorful, laid back and chic,” said Brazilian-born fashion consultant Abraao Ferreira. “They’re the quintessence of everything that people find appealing about Brazil.”

The numbers speak to that enduring popularity.

Last year, 210 million pairs of Havaianas were sold worldwide. Even with 15 percent of total production exported to some 80 countries, enough of the sandals were sold in 2011 for nearly every man, woman and child in Brazil.

Legend has it that Havaianas’ simple wishbone between-the-toe design was inspired by Japanese “zori” sandals, the traditional straw-bottomed footwear worn by geishas.

“It’s true that some executives from (parent company) Alpargatas took a trip to Japan before the launch,” in 1962, said Rui Porto, a longtime company executive who now works as a media consultant for the brand. “But the origins of this style of sandal date back to the dawn of time, to roughly the same era as the invention of the wheel.

“In fact, that’s why there’s no patent on them,” Porto said.

Still, patent or not, Havaianas has kept the formula behind its squishy rubber soles a tightly guarded secret. Since most of its direct competitors make cheaper, plastic-soled flip-flops, Havaianas’ aerated rubber soles are seen as key to the brand’s success and their manufacturing process is kept under strict wraps.

Beyond acknowledging they’re made from a mixture of domestic and imported rubber that shrinks and hardens with extended wear, Porto declined to provide any details about the secret soles.

In the beginning, Havaianas came in a Spartan palette, their white soles paired with either sky blue, black or yellow straps. Sold in popular street markets, they quickly became such a basic for the poor here that they were included on the list of basic necessities such as rice and beans that the government used to calculate cost-of-living increases.