Well, she's not a new sultry lady, she's an old one now, but she's the one that Diana Krall holds in high esteme, and in my estimation, trys to emulate (unsuccessfully), Shirley Horn. She's a bit more laid back but she's the real thing! She is an excellent piano player, singer, and stylist. Three CD's to start with - "I thought about you", "Close enough for love', and "You won't forget me". all on Verve.
Three other jazz current singers well worth listening to: Mary Stallings, Rene' Marie, and Tierney Sutton. These gals should be around a while judging from their current limited catalog (3 or 4 each).