After years of taking it on the chin, the U.S. costume jewelry industry is starting to shine in the international arena.

Last year, exports of American-made costume jewelry jumped 26 percent over the previous year to $53 million. The International Trade Commission also reports that industry imports rose only 3 percent to $73 million.With this in mind, the International Jewelry Trade Association of America, based in the Providence, R.I., suburb of Johnston, has launched an aggressive marketing strategy to capture an even larger share of the pie, or increase revenues by making the pie bigger.

The association has launched a series of trade shows for domestic and international buyers, buttonholed U.S. government officials to spread word of American products abroad, and plans a $15 million trade center for Rhode Island.

"(Foreign sales) could be a major part of new business," association director Harold Howland Jr. said. "But another major part would be U.S. wholesalers and retailers who are now buying foreign products. We're trying to make it easier for them to buy them here."

For decades, costume jewelry was regarded as the stuff people bought when they could not afford the real thing. And the heart of the industry was the Providence area, where about 50,000 people still work in costume jewelry manufacturing plants along Narragansett Bay.

But according to Mitch Plotnick, associate publisher of the monthly trade magazine Accent, based in Devon, Pa., that began to change in the 1970s, and the metamorphosis accelerated in the 1980s.

"The term `costume jewelry' in this industry is really outdated," Plotnick said. "It referred to jewelry that looked real but was not. Fashion jewelry is geared to accesorizing seasonal clothing trends. Today, to be in the fashion jewelry business you really have to be a student of clothing."

Also, while the Providence area remains the manufacturing center of the industry, New York has become its rival in terms of showrooms and sales, while companies in the Southwest and California have entered all phases of the market.

The reason for the expansion is obvious: money.

According to Plotnick, the costume jewelry industry saw an average annual growth rate of 8 percent at the retail level from 1983 through 1987.

But as fashion jewelry became more attractive to buyers, it also caught the eye of more foreign manufacturers. Imports account for about one-third of domestic costume jewelry sales, more than double 10 years ago.

Plotnick attributed the rise in American-made costume jewelry sales abroad last year to a more favorable exchange rate and a "fascination" among Europeans and Japanese with the "American look in fashion accessories."

But he added that imports are here to stay and "will always be more price competitive than American goods."

"The non-progressive manufacturer sits back and does nothing," he said. "The more aggressive is looking into opportunites abroad or expanding retail outlets in this country."