There were no tears, no fainting, no hysterics. Yves Saint Laurent, performing a patriotic service for his country, yesterday restored American buyers' faith in French fashions. $ winding up a week of showings for next spring and summer that sometimes produced bizarre designs, theatrical presentations, and buyer disbelief, Saint Laurent won much applause by making just enough changes in his designs from past seasons to entice his aficionados to part with their money -- lots and lots of it -- without shaking their confidence in what they already own.

Saint Laurent's strenghth was in his diversity. His skirt lengths were safely at the knee, a length many women find comfortable and flattering. And his new twists on past styles offered appeal. A peasant skirt, for example, was now hiked to one side.

Saint Laurent borrowed from his highly successful couture show in July which, according to reports caused a few women to take out their scented handerchief to dab tears of joy. From that show, YSL has spun off his bicolor clothes, sometimes in black and white, sometimes in two strong shades.

It was only fair that he should, since everyone else is copying those color blocks this season. And fair, too since it was YSL, in the early 1960s, who made straight-black, stiffly structured sheaths decorated with color blocks a la Mondrian. Now he divvies up his suits in color segments with homage to Picasso.

"yes," said Picasso's daughter,Paloma, who was in the front row for the showing. "The colors are precisely Picasso and so are some of the prints. And the tricorn hats from the Diaghilev Ballet, "Tricorne," with the music by Falla, for which my father did the costumes."

The hat resembles the colonial three-cornered hat. "It looks like Saint Laurent has been to Williamsburg with a Latin American interpreter," teased Geraldine Stutz, president of Henri Bendel. She was referring to the ruffled and tiered skirts, the peasant blouses and the lace-up, coret-like tops that had surfaced earlier as part of Saint Laurrent's famous Russian peasant look.

Saint Laurent is back with knickers and bloomers, which he has done often before. But now he has a new taffeta he uses for blouses -- a laquered shantung made for him byGustav Zumsteg of Abraham. It has the shine and shaping quality of the oldtaffeta, but is lighter and more iridescent.

His multiclor harlequin sweaters are guaranteed to be the next big sweartshirt sytle, and his wide belts, his rope-and-bead necklaces, his white stockings and his low-heeled black-patent pumps are assured a secure place in the closets of many American women the next time the weather warms up.

All these good wearable clothes do not stand in the way of Saint Laurent having his fun, if not with the craziness of some of his colleagues, at least with some humor. At least we hope he was teasing when he showed, for example, ruffied bikinis with a fishtail to the ground, worn with fishnet hose and high-heeled shoes.

"His clothes are very costumey and very good," said Kay Kerr of Neiman-Marcus, after the presentation. "But that makes his clothes hard to wear. She didn't think it would inhibit any purchases, however. "Women love to wear his clothes that have a very strong signature. When women pay that price, it is nice to be recognized."