Gray--conservative, a shade mature, successful and secure--is a Washington color. It's the color of granite, the color of concern. Gray can be foggy and unclear, but it can also be quiet and safe. Think of gray clouds, gray flannel, the gray scale. What always matters is gray matter.

But which of these is the reason for fashion's going gray this season? None of the above, alone, but a dash of each. Gray took over--forgive us, please--like a greyhound, as a way to shake loose the well-entrenched palette of that secure, well-established color black.

Gray, after all, is just another shade of black. But it has different roots--unexpected and untraditional. It has been a dominant theme of the aggressive, innovative designers and stylists on the horizon, the Japanese, who started with a clean slate by building new forms, new textures and by making gray a new color. Primed with ancient weaving and dyeing techniques, Japanese designers have created a modern mix that is the antithesis of good old gray.

And so these clothes for next fall are not the expected and familiar. Yes, there is gray flannel, but it is sometimes meant to be worn for evening, refreshed with sparkle and shine or paired with glitter and glitz. Subdued gray becomes the new color of the night: for men, with gray shirts or ties even with formal garb; for women, with jeweled gray tunics or sweaters, often teamed with flannel or satin trousers--gray, of course.

The new grays do not fall in the shadow of success- dressing or the banker's gray suit. They are bold and independent, not safe. If you own one classic gray pin-stripe suit, one board-room suit, why buy a carbon copy? As expensive as clothes have become, the investment should be for something splendid and special, rather than a repeat.

For women the sweater can take the place of the suit jacket this season; the knit dress sits well in the board room. A new skirt is long and pleated, not straight and severe. The new jacket is often short and fitted, a far cry from the classic blazer. Gray sweaters, gray jackets and gray shirts may sound safe, the same old stuff, for men-- until you catch the shapes, the fiber blends, and the independent way of wearing them.

There are so many shades of gray, the range is downright colorful. From charcoal gray to platinum. From strong-as-steel gray to soft dove gray. Some designers have mined a deep anthracite gray; jewelry designers have found wonderful things to do with gun-metal gray. This season silver has a higher fashion value than gold.

Gray is a perfect neutral; with a pair of gray flannel trousers this season you have half your wardrobe. Gray softens the harsh tones of items already in your closet and clouds the dated look of others. What looks freshest with gray this season: black and white, which are, after all, the basic ingredients of gray.

Where to go when you are feeling gray? We took off on the aircraft carrier, Intrepid --all done up in battleship gray, with a dash of bright colors and a lot of Navy. Now a museum of sea, air and space technology, it provides plenty of space for parading in gray. It is three football fields long and 15 stories tall. A perfect place to spend a gray--or sunny--day. CAPTION: Picture 1, CLASSIC GRAY FLANNEL MAKES AN unexpected appearance for evening, brightened with satin and jeweling in a dinner suit with silver lam,e blouse and gray flannel trousers by Richard Assatly for Benton at Saks Fifth Avenue and at Raleighs, Connecticut Avenue; crystal drop earrings by Mark Spirito at Saks-Jandel; Pictures 2 and 3, IT'S THE SWEATER SEASON AGAIN, BUT THE SWEATERS THIS TIME--ALONE or in sets--are long and lean. For men, the new twist is patterns, both bold and subtle.

This sweater set by Gloria Sachs pairs a cashmere crewneck sweater and cardigan sweater, sharply edged in steel gray, worn with an ombre stripe brushed wool skirt, all at Neiman-Marcus; black wool sailor hat and charcoal cashmere muffler both from Gloria Sachs, to order at Neiman-Marcus; gloves by La Crasia at Bloomingdale's; silver earrings with black stone by Mark Spirito at Saks-Jandel. His lambs-wool sports shirt by Alan Flusser at Britches of Georgetowne; windowpane-check wool trousers by Perry Ellis at Neiman-Marcus.

The zebra-patterned wool pullover by Perry Ellis is at Bloomingdale's; Basco's bold geometric, nub tweed turtleneck, designed by Gene Pressman and Lance Karesh, is at Cedar Post; Pictures 4 and 5, DRESSES WITH THE EASE OF A CHEMISE: WOOL JERSEY SWEATER DRESS with leather insert by Samuelson & Abrams at Woodward & Lothrop; earrings by Bonwillum at Dolly Kay Designs. Cowl-neck wool jersey dress by Issey Miyake for Plantation at Bloomingdale's and La Boutique Francaise; belt by Bonwillum at Dolly Kay Designs; earrings by Stephen Dweck at Saks-Jandel.

Cathy Hardwick's dolman-sleeve wool dress with flip-top neckline at Ann Taylor; gloves by La Crasia at Bloomingdale's; earrings by Jay Feinberg at Saks-Jandel. His wool shirt is by Randy Allen at Commander Salamander; Picture 6, BARELY A trace of the old dress-for-success formula is found in the new suits. A good example is Bill Haire's flannel suit with fitted jacket, knife-pleated skirt, with a mohair crewneck sweater worn underneath, at Garfinckel's; silver drop earrings and silver link bracelet, both by Isaac Manevitz for Ben- Amun at Impulse and at Bloomingdale's; wool jersey elbow- length gloves by La Crasia at Bloomingdale's. His giant- houndstooth wool jacket by Alexander Julian at the Alexander Julian Shop, worn with a cashmere sleeveless vest, wool tweed tie and flannel pants, all by Perry Ellis at Bloomingdale's; gray cotton shirt with turquoise and brown stripes by Ron Chereskin at Woodward & Lothrop; Pictures 7 and 8, THE LONG WOOL-JACQUARD morning coat and wool skirt, by Miya & Co. at Saks Fifth Avenue and Cachet Four Seasons; ebony graduated-disc necklace and unfinished maple earrings, both by Bonwillum at Dolly Kay Designs; wool jersey elbow-length gloves by La Crasia at Bloomingdale's. His wool double- chalk-stripe, double-breasted jacket and pants, gray, white and wine striped shirt, printed silk tie, all by Alan Flusser at Britches of Georgetowne; Picture 9, COATS ARE CUT generously to cover all this season. Huge collars give an important balance to the full-coat silhouette. The coat for all seasonal changes, wet or dry, is Harriet Winter's cape-collar short coat in wool with a weather-resistant coating of gray plastic, for Yesterday's News at Lord & Taylor; Aris Isotoner wool knit gloves at Woodward & Lothrop; Picture 10, LONG, BELTED, WOOL AND MOHAIR blend "spy" coat by Catherine Hipp and wing turtleneck wool sweater, both at Cachet Four Seasons; gun-metal and brass triangular earrings with stone inset by Tulla Booth at Impulse and Nikki Young's; Picture 11, THE SCARF COLLAR, above, is the only closure for Yeohlee's knee-length coat, at Jackie Chalkley and Cachet Four Seasons; fur hat by Lenore Marshall at Garfinckel's; black wool jersey elbow-length gloves by La Crasia at Bloomingdale's; Picture 12, FOR IMPORTANT occasions, gunmetal sequins, add a soft glow to Bill Blass' tunic, to pair up with gray flannel pants, at Saks Fifth Avenue and Neiman- Marcus; gray mother-of- pearl earrings by Stephen Dweck at Saks-Jandel. His wool trench coat is by Perry Ellis, available through Bloomingdale's; Picture 13, THE CASHMERE sweater becomes a front for handsome graphic in a slate and platinum gray bisected pullover with multicolor geometric patterns by Alexander Julian at the Alexander Julian Shop; Picture 14, TWO coats are better than one when each one can be worn independently as well as together. Hers is a black and gray canvas double coat by Samuelson & Abrams worn over a gray gusset jumpsuit by Claudia Reid, both at Silhouette; black mink trooper's hat by Lenore Marshall at Miller's Furs; silver-studded double belt by Marty Ruza for Elegant Creations at Cachet Four Seasons; gun-metal triangular earrings with purple gem by Tulla Booth at Nikki Young's and Impulse; charcoal wool voile fringed scarf with magenta print by Echo Scarfs at Lord & Taylor. He is wearing Willi Wear's black and gray oilcloth double coat and Randy Allen's black high- neck cotton poplin shirt and black brushed cotton pants, all at Commander Salamander; Picture 15, WINNING STRIPES IN several shades of gray wool are shaped by Calvin Klein in a shirt and matching skirt with released pleats at Bloomingdale's and Woodward & Lothrop; ebony soft square earrings by Bonwillum at Dolly Kay Designs; black belt by Calvin Klein at Harriet Kassman and Bloomingdale's; jersey gloves by La Crasia at Bloomingdale's; Pictures 16 and 17, COLOR BLOCKING IS A SHADE MORE modern when the tones are anthracite, steel and platinum in silk faille, worn with a narrow faille skirt by Tadaomi at Cach,e; pearl and jet earrings by Tess Designs at Garfinckel's. His chenille jacket and trousers are by Jhane Barnes, at Bernard Hill.

Right, the unmatched suit mixes textures and tones in Jhane Barnes' "Fast Lane" jacket with striped body and solid charcoal sleeves and tweed trousers. Shirt and silk tie also by Jhane Barnes, all at Bernard Hill; Picture 18, THE TOPPER that tops all others is fingertip length pewter-dyed sheared beaver coat with low-notched lapel collar by Chlo,e by Karl Lagerfeld at Saks- Jandel; hematite and frosted rock crystal earrings by Stephen Dweck at Saks-Jandel; Picture 19, GRAY MAKES A grand entrance when striped with silver sequins in a tunic to be worn with gray flannel trousers, with a matching skirt--or with nothing, as we've shown it--by St. Martin for Rod Owens at Saks Fifth Avenue; black irregular- shaped earrings, jeweled black cuff and black sequin belt, all by Jerry Kott at Smull's; Picture 20, AN ALLOY OF MANY METALLIC threads makes a handsome textile mix by Geoffrey Beene for evening with a gray quilted long evening coat with silver pann,e velvet lining, pewter and charcoal metallic chiffon blouse and full tucked pants in pewter silk taffeta print, at Elizabeth Arden; hammered gun-metal earrings by Isaac Manevitz for Ben-Amun at Bloomingdale's and Impulse; Pictures 21 and 22, TWEED is an easy weekend alternative--but now in sweaters instead of sports jackets.

Black and gray cotton-knit pullover by Issey Miyake Plantation, to order at I. Magnin; black acrylic knit scarf with magenta print by Echo Scarfs at Lord & Taylor.

Mix black and white for a gray wool tweed crewneck sweater rimmed in burgundy by Adrienne Vittadini; Vittadini sweaters at Woodward & Lothrop; Picture 23, STEEL GRAY IS THE COLOR but the touch is soft as skin in Ron Chereskins' front-snap leather jacket, shown over a gray plaid wool shirt and gray corduroy trousers, collection at Woodward & Lothrop; gray beret at Hats in the Belfry. MAKEUP BY MARIA DE SCHNEIDER; HAIR BY DANIEL TAFT AT CLIVE SUMMERS, NEW YORK. PHOTOGRAPHED ABOARD THE INTREPID MUSEUM, NEW YORK. Photos by Michael O'Brien