BY RAY LUSTIG -- THE WASHINGTON POST Epitomizes casual chic. Three-piece ribbed-cotton knit ensemble comes in navy, cream or taupe. Long cardigan, $32; leggings, $28; tank top, $14. At the Gap -- Five Oaks, Seven Corners and Georgetown. no agate credit It's the thing to do. Wearing a bikini, that is. The best ones this year have a strapless top and come in bright, bright colors. This one, in thick nylon/Lycra, has bold vertical stripes. By Raisins, $38.99 at Island Water Sports, 3005 M St. NW. BY RAY LUSTIG -- THE WASHINGTON POST Time for the big watch. They are not only trendy, but useful for the far-sighted. This one is called a "Pop Swatch" because it snaps out of its case and becomes a pocket watch. By Swatch, $35 at Bloomingdales. BY BILL O'LEARY -- THE WASHINGTON POST If you think peau de soie is too dowdy, then try dyed-to-match lame'. Just bring a small swatch of fabric to the store and voila': matching metallic pumps, $48; purse, $24; hair bow, $15, and shoe bows, $11. By Dyeables at the Hope Chest, 129 So. Royal St., Alexandria. BY BILL O'LEARY -- THE WASHINGTON POST Button up your shirt and stick it with a pin. Colorful pin collages of handmade paper knotted and fixed in resin. By Two Women, San Francisco. $15.50 at Ginza, 1721 Connecticut Ave. NW.