A small, family owned plating company in Rhode Island has gone gold under an exclusive contract with giant carmaker General Motors Corp.

Tanury Industries, of Lincoln, R.I., whose sales have soared from $196,000 in 1974 to $12 million this year, is now exclusively supplying the nation's top carmaker with the latest in automotive excess - 24-karat gold-plated nameplates and emblems for its new Cadillacs.The arrangement capitalizes on the growing number of luxury car buyers who are personalizing their automobiles by having the vehicle's nameplates, insignias and model designations replated in gold for a richer, more exclusive look.

"Such customizing can cost owners between $400 and $1,000 per car," said Paul Colarusso, an engineer with Tanury who worked with GM during the past 15 months to develop a high quality plating process that would not reflect poorly on Cadillac, which has been trying to recapture from European carmakers its status as one of the top luxury nameplates in the world.

The company also has developed a program that allows buyers to order gold ornamentation directly from Cadillac as a $395 factory option, instead of having to go to aftermarket companies that sometimes provide inferior plating which tarnishes or corrodes quickly.

Gold-colored ornamentation on automobiles, especially Cadillacs, first appeared in the late 1950s, Col-arusso said. But those early efforts were of low quality and such plating faded from use during the 1960s and 1970s.

During the 1980s, gold began to regain favor as buyers of both domestic and import luxury cars sought to personalize their vehicles through `special edition' or `designer' packages. Once again, the gold rush was on.

Colarusso, whose company had been providing Cadillac with gold-plated car keys for about five years, helped GM engineers establish a rigorous set of standards for the Cadillac emblems.

Those GM standards call for each gold-plated piece to be able to withstand more than 300 hours of salt spray, 300 car washes, 168 hours of humidity, and two hours of water immersion.