You've heard of Charlie and Babe, now how about Bianca? Bianca Jagger (the estranged Mrs. Mick) has been taking a perfumery course in London and is plotting a perfume, to be named Bianca of course. She has only to consult her best pal Halston for a graduate course on how to market a fragrance successfully. She has recently filmed "Ringer," is being considered for a part in "Bloodline" (with James Mason) and says that more than just making the party scene, "I finally know something. I'm finally going to make it as an actress."

"I kept seeing such poorly made clothes coming across my desk, I just had to start making things myself," says Steven Losch, former fashion illustrator, who admits that one day he was slopping the hogs, the next day sewing silks. So he's turned designer/manufacturer with partner Saint Elizabeth's psychologist Vincent Thomy for his menswear and Garfinckel illustrator Amie Ambrose for his women's. Now there is a collection of dresses in hand-painted crepe de chine, loose fitting and getting their shape from an elasticized waist or from knotting done individually by the wearer. Liberty (Georgetown) and Mamori (Capitol Hill) have the dresses as well as his shirts.

Footnote on the Coty Awards ceremonies: Perry Ellis wore Topsiders, Mary McFadden had on platform shoes and menswear designer Robert Stock was wearing red velvet slippers monogrammed in gold, with his tuxedo. "I've had them several years and couldn't think of many occasions to wear them. But tonight somehow seemed right," said Stock.

Speaking of shoe biz . . . the hottest single seller to step out in a long time is the Candie, a cha-cha heel on a plastic sole held in place only by a wide leather vamp. Shoe Scene has sold 3,200 pairs in two stores, the maker, El Greco, has sold 2 million pairs in three months. Georgetown University preppies (girls) wear them with their jeans and shetlands, secretaries and other downtowners with their dresses, suburban shoppers with their corduroys, disco-goers with pegged pants or Danskins.

The reason? They are sexy and they are cheap ($16) and, in spite of the clatter they make, they are comfortable. Because of the molded sole the heel isn't as high as it looks. Among other stores that have them are Hecht's, Woodies, Garfinckel's and The Bootlegger.

Studio 54 disco garb has landed at The Pier in Washington. The skinniest stiletto pants, often made in strech Lycra spandex to ensure their tight fit, are worn here and there, with bantam-weight loose fitting tunics or tuxedo shirts, and of course, the ubiquitous cha-cha heels. (The pants are available at stores like Casual Corner, Ups & Downs and I. Magnin.)

If New York is where it happens first, but we can look for young women here to start wearing body-conscious, split-up and slit-down dresses, the kind we used to call cocktail dresses, to the office with bare high-heeled shoes. It's all the rage in New York, not because women there are running directly to the discos from work. Just because they like the sexy look.

What makes clothes look sexy? Yves Saint Laurent says if there is one thing more than anything else, it's black stockings, year round. "I don't know of anything sexier in the summer than a woman wearing black stockings with a white skirt," he says.

YSL also finds women in man-tailored clothing very sexy. "Somehow a woman makes more of an effort to look more feminine, more seductive, because of the mannish style of clothes, than if she were in a low-cut dress."

"Can I wear a white dress to a wedding?" We had three calls on that subject one day this week. The textbooks on the topic would say positively no, but the reason has always been that there might be some confusion between the guest in the white dress and the bride. If no one is likely to confuse you with the bride, why not wear white! Besides, there are a fair share of today's brides (second marriages, older women, etc.) who don't wear white themselves. (There's also been some question about black - black was banned for looking to funeral at a wedding, but few black dresses look that way today.)

"Some guidelines, please, now that I'm really shopping seriously for fall clothes." Another favorite plea to this office. We'll bet your eyes will soon be attuned to narrower pants, narrower and shorter lapels and collars and everything a bit skinnier generally. If you need standards, those are as good as any.

The devil in "Damn Yankees" made red socks noticeable. Halston is making them chic. In the first issue of the renewed Life magazine, Halston, wearing red socks, is pictured in bed as well as in his living room being served Perrier by his butler Mohamad. (Red socks also made the list of what's "in" for men in "W," an off-shoot of Women's Wear Daily. Red underwear did, too.)

What's out? For some Georgetown lady, it's Ultrasuede. A city garbage collector collected ten Ultrasuede dresses from a heap outside a Georgetown house this week. All were obviously worn, but in perfect condition. (Check your local second hand stores.)