reported at his pre-fall presentation that sales of his resort line have been brisk, with, he says, 50 to 60 percent sell-throughs in just three weeks. There's no denying that the 27-year-old designer is hot, but the important thing is that he's intent on not just coasting along. There's his new 9,000-square-foot Garment District showroom and studio, for starters. And then there's his pre-fall lineup itself, which has a harder edge than his fans may be used to, thanks in part to his use of leather, a material he's working with for the first time. The collection's showpiece is a silver leather cocktail number laser-cut with a feathering technique that makes it look like panne velvet. It's available in an "editorial" 18-inch length, as well as a more conservative 23-inch option, like all of his dresses. Wu also made a big push into separates. A "two-in-one" short-sleeve sweater with a long-sleeve jersey knit built in underneath topped a mini, which was made from sequins that had been bent and covered with chiffon to evoke feathers. Sharp-looking blazers, meanwhile, were cinched with leather belts and paired with short shirtdresses or skirts. Positive developments, all around.