In the retail business, they call watches a mature industry. Everyone's got one. No one needs another. Then Timex invented Indiglo: a watch that lights up at the push of a button.

And the market changed.

It took Timex 20 years and $8 million to develop and patent the Indiglo technology. It's more than a simple phosphorescent coating. It's a light bulb that's paper-thin and works on battery power. A Timex spokesman says it's "the first true innovation in watches since quartz technology."

In the four years since Timex introduced Indiglo, the company's share of the watch market has increased from 25 percent to 35 percent. In three years, Timex increased its advertising budget -- already the largest in the watch industry -- from $13 million to $20 million. Tales of the dim light from an Indiglo helping to save lives in times of crisis have become urban legends: people finding their way to safety after an earthquake, thanks to the glimmer of an Indiglo; without electricity, doctors operating by the light of Indiglos.

Now Timex is working on its hipness quotient. It's taking a lesson from companies such as Keds and Hush Puppies, which have benefited from the fashion industry's fascination with retro styles.

Timex looks ready to become the next brand of the masses to be embraced by fashion insiders. The maker of watches with plain faces and flexible metal bands may be on its way to becoming cool. And Timex is working hard to make sure that happens.

Several seasons ago, the company became one of the sponsors of New York's 7th on Sixth -- the organizers of the city's womenswear runway shows. Not only did the sponsorship put the Timex name in front of fashion designers, editors, stylists, retailers and photographers, but Timex also put its watches on their wrists. The company has been including sample watches -- Indiglos and others -- in all of its promotional material. Its most recent fashion offering? A silver-colored watch with a delicate, miniature face and a slim, metal stretch band. It was designed to coordinate with the clothing industry's focus on trim, ladylike suits and feminine sweater sets.

The test, though, was whether fashion folks would wear the simple timepieces. They did and they do. Sometimes trends can bubble up from the street, but more often they begin on the body of a stylist -- one of the trendmakers who select clothes and accessories for, among other things, music videos and magazine fashion shoots. These are the people who made Prada purses and Chanel's Vamp nail polish must-haves.

Now Timex -- downscale, utilitarian and basic -- is sharing an occasional fashion photo with the hot Gucci label. And so it begins, the birth of cool. CAPTION: Trend watch? Indiglo by Timex, clockwise from far left: women's black-faced watch, $40.95; women's metal bracelet, $60.95; men's watch with a leather strap, $39.95.