Why, I wondered, would Jessica Williams interrupt her soaring solo career to record an album with little-known Seattle singer Carolyn Graye for a tiny West Coast label? Friendship, perhaps? Williams did, after all, add dazzling accompaniment to two tracks on Graye’s eponymous 1996 debut. Though you’d never know it from reading the back of the CD, turns out the 10 tracks that fill Graye’s Songs (OA2) are of the same vintage. They ably demonstrate why Williams ranks among the most respected pianists of her (or perhaps any) generation. Her interpretations of such standards as “That’s All,” “Alone Together” and “Get Outa Town” are gorgeously distinctive and distinctively gorgeous. Trouble is, she’s simply too accomplished for Graye. That’s not to suggest that Graye’s not a capable, indeed impressive, vocalist. A widely respected jazz analyst (who, currently completing her Ph.D. in musicology, will soon become Dr. Graye), she has a duskily appealing voice and a keen skill for lyrical interpretation, especially on a mistily despondent “Everything Happens to Me” (slightly spoiled by her corny modernization of the final verse). But the disconnect between her and Williams is so distinct that it often sounds as if the two women were simultaneously working on separate albums.