Best-Dressed in Supporting Roles : Fashion: New options allow the mothers of the bride and groom to look good without stealing the show.

Mention “mother of the bride” to glitter-and-glitz designer Bob Mackie and he chuckles as he recalls “those dreary dresses we used to see on mothers of the bride in the movies. Well, it’s not like that anymore. There’s a lot of figure showing.”

Happily for everyone, “the powdered-down laces and dumpy, conservative evening dresses” Mackie remembers are almost an endangered species. These days, mothers of both bride and groom waltz down the aisle in chic options--ranging from beaded gowns to brocade suits--looking every bit as glamorous as the event’s leading lady.

With a better figure, younger face (real or realigned), greater freedom and more choices than her mother ever had, the problem for today’s mother of the bride or mother of the groom is ensuring that she plays the role properly: not too understated, not too overblown. The stylish woman often gets it right by following her customary fashion instincts.

“If she’s an Armani woman, she wants something that looks like Armani,” explains Hedda Kleinfeld Schachter, co-owner of Kleinfeld’s, the country’s leading bridal store, in Brooklyn, N.Y. “She would usually go for a very fine cut and an interesting fabric rather than a lot of decoration. But the majority of our mothers want decoration. They want to be noticed. Not above their daughters, but to cheer up the picture, to accessorize it.”

Bridal specialists tend to talk in terms of “the picture.” And, yes, they really do mean photographs, as well as the overall effect.

Discussing black, a color considered socially correct for hotel or other sophisticated indoor weddings, Schachter explains: “I don’t like solid black. It doesn’t photograph well. And black is awful if it’s too close to the neck.” She likes something softer, such as black lace over a layer of nude-colored silk.

The all-white or all-ivory wedding “is super-popular in Los Angeles and New York, and it creates a beautiful picture,” Schachter says. “It’s more fantasy, a real Cinderella ball. The mother of the bride could wear something in white or ivory chiffon, satin or taffeta with a little gold trim.”

Mackie, however, finds all-white nuptials “a little boring. I’ve seen it look pretty, but I would rather the bride pick a color she likes and have it go all through the wedding.”

This spring and summer, he offers long gowns with draped bodices and full skirts in ombred chiffons that go from pale periwinkle to a richer, darker shade of blue or from fuchsia to pale pink. There are also embroidered jackets worn over long, strapless gowns. Definite lengths, long or short, says Mackie, “look appropriate and snappy,” something he feels “droopy tea-length dresses and handkerchief hems” don’t accomplish.

But tea length (technically anywhere from below the calf to above the ankle) is popular with mothers. “It’s a comfortable length to wear,” says Verna Husan, owner of Mon Amie in Costa Mesa.

Husan’s customers like the hemline for “pretty soft suits,” although they also wear suits, one of the newest additions to the bridal repertoire, with skirts that hit just below the knee.

Barbara Tober, editor of Bride’s magazine, calls a suit in silk, organdy, organza, chiffon, or made from a combination of two or three fabrics, “a whole new look for daytime weddings. For an afternoon wedding, it might have one of the wonderful new lace collars, or a glint of gold or silver.”

For evening, the suit look can be translated into something such as a dove-gray satin beaded jacket over a dress with spaghetti straps, or a scoop neckline, and additional beading on the bodice.

With weddings becoming more frequent and more elaborate, bridal specialists across the country--including Ferndales in Orange, Victorian Garden in Studio City and Susan Lane in Toluca Lake--are offering an impressive range of garments, priced from $50 sale dresses to $4,000 designer gowns. And some specialists do more than just order the color and size a mother wants.

Renee Strauss, co-owner of Renee Strauss in Beverly Hills, creates “custom couture,” from $1,500 to $2,500, and often for the larger woman. Her store also offers custom millinery by Mark Valerio, “who did hats for Nancy Reagan,” says Strauss.

At I. Magnin, one of the few department-type stores in the country left with a bridal salon, women can opt for the unique, if they choose not to buy something along the lines of a draped, chiffon-print by Holly Harp or a pleated and lightly beaded Mary McFadden gown. One mother recently requested that Arnold Scaasi design a black-and-white gown exclusively for her. Bridal buyer Patti Miller explains: “Her daughter will wear a Scaasi gown with a marabou skirt and a white satin bodice. It’s the type of dress that needs something special.”

Marabou-clad bride or not, special is what every mother wants. But not so showy “that it takes away from the bride,” says Barbara Charlton, a professional model and mother-of-the-bride. For her daughter’s August wedding, Charlton is making her own tea-length, teal chiffon dress with nothing more showy than a jewel neckline and butterfly sleeves.

June Van Dyke, a two-time mother-of-the-groom and former associate of costume designer Edith Head, says her daughters-in-law set the tone for their weddings by choosing “very elegant, but simple gowns. They weren’t fussy or grand.”

Van Dyke’s own choices were equally elegant and simple: a Bob Mackie hot-pink-and-cream silk dress for one wedding; a Valentino pinkish-cream silk dress for the other. And she still wears them.

But whether the dress comes from Valentino or a Vogue pattern, bridal experts say there are several mistakes to avoid.

Kleinfeld’s Hedda Schachter cautions “women shouldn’t buy the wrong cut for their figures by becoming enamored with the color or some decoration on a dress.” Trust the experts, or bring along “some of your old-time friends. They can tell you the truth. They are looking at you, which is different from you looking at yourself in the mirror.”

Prints for evening “should be gentle, like watercolors. But for afternoon, they don’t have to be quite as soft,” Schachter advises.

And women who can’t afford more expensive garments, which often run $600 to $1,900 at Kleinfeld’s, should look past the imported silks to “fabrics that are not expensive but look it.” These include good-quality polyester chiffon, polyester taffeta, rayon crepe or satin-backed crepe.

Designers known for keeping the price down include Victor Costa, Richilene, Jessica McClintock, A La Carte and Miss Elliette. (She seems to be everyone’s moderate-priced favorite, including Strauss, who doesn’t even stock the label).