Contrary to recent rumor, diamonds, minks and tuxedos have not completely shoved turquoise, suede and jeans out of vogue this year.

In fact, the Reagans being from California, and frequently horseback-riding and all, have actually helped the cowboy business.

Ask Ralph Lauren.

He flew to town last night from New York with 30 models, 10 racks of frontier skirts and western shirts, and boxes full of boots and turquoise to show part of his Santa Fe collection. Not to mention the 1,500 pounds of barn siding with which he had a stage built.

"I think that Americans love the western and rugged way of life. It represents an attitude for them," said Lauren. "The fact that the president of the United States is from California puts forth that image. It certainly doesn't hurt."

Lauren's companies and Warner Communications underwrote the foot-stomping, rib-chomping evening -- "An American Western Celebration" -- to benefit the National Committee, Arts for the Handicapped, a longtime Kennedy family project. The top New York models alone cost $30,000.

Committee secretary Jean Kennedy Smith wore a Lauren Annie Oakley black velvet dress and lots of Lauren's turquoise jewelry.

"I just love him," said Smith. "Nothing can replace his western wear, in my book. I wear all his clothes. He's the best sportswear designer around."

Smith estimated that last night's event would clear in excess of $50,000 for her organization. Tickets ranged from $100 to $500. She said the money would be used for grants for states to set up arts festivals for the handicapped. "The important thing is to enable the handicapped to get involved with the arts," she said. "So far we have 28 states involved and we'd like to get the whole country."

After Lauren's 80-outfit fashion show, guests settled down to a western barbecue of chili, ribs, chicken tacos, salad and brownies, and performances by the Gallaudet College dancers and Michael Murphey and the Great American Honky Tonk Band.

Among the other guests were Phyllis Wyeth, pianist Peter Duchin, Shirley Jordan, wife of Vernon Jordan, and Manny and Betty Ourisman.