This came from a gem care site:
Care
Tourmaline is a hard gemstone that is resistant to both scratching and breaking, but it should be protected from sharp blows or sudden changes in temperature. Because of the natural internal characteristics found in some tourmalines, especially pinks and reds, ultrasonic cleaning machines should not be used. Tourmaline can be cleaned with most any commercial jewelry cleaner or plain soap and water using a soft brush.