The last time Cassandra Wilson attempted an album devoted purely to standards —Blue Skies from 1988 — she played it uncustomarily safe. Loverly, a new standards project, displays the considerable distance this acclaimed singer has come over the years. Loverly calls on the idiosyncratic mix of acoustic and electric instrumentation and rural blues inflections that her fans have become familiar with since the 1993 breakthroughBlue Light ?Til Dawn. The repertoire may draw from the likes of Lerner & Loewe and Harold Arlen, but the performances abound with folk and slide guitars, hand percussion, and the unconventional piano work of Jason Moran. In other words, off-kilter sheen on familiar material — an approach that Wilson, in excellent, customarily laid-back form, takes to with second-nature glee. She also allows herself more freedom by wisely extending the standards concept to include the bluesy “St. James Infirmary” and “Dust My Broom,” the Latinized Ellington hit “Caravan,” the bossa nova warhorse “A Day in the Life of a Fool,” and her own percussive original “Arere.” The most resonant performances are the simplest. Accompanied only by the Joni Mitchell–esque guitar work of Marvin Sewell, Wilson delivers a “Spring Can Really Hang You Up the Most” for the ages; while “The Very Thought of You,” with the lone support of bassist Lonnie Plaxico, displays the sensuous ease that no jazz singer of her generation has yet to match.