Last week, shortly after I snatched this Marni skirt off Nordstrom’s 60-percent-off rack (yes, Nordstrom carries Marni!), I complimented my stylish saleswoman on her Roland Mouret dress. She leaned toward me and said, sotto voce: “It’s not Mouret. It’s Black Halo. And it’s a fraction of the price.”

How could I possibly have been unaware of Black Halo’s Jackie sheath, which since its introduction in 2006 has been written up by everyone from InStyle (“Hollywood loves this dress!”) to the Wall Street Journal (“The dress that never quits”)? The figure-hugging poly-spandex number is sexy but still ladylike, thanks to squared-off cap sleeves, an interestingly asymmetric neckline, and a modest knee length.

While it’s available in colors and prints galore, black or cobalt (pictured) is the classic choice.

$345 at Nordstrom, 520 N. Michigan Ave., or