ZIMMERMANN 2015/03/18 There were once many pianos with ivory white keys. The major features of ivory white keys are; 1. White key surface absorbs sweat. 2. Friction force helps to prevent fingers from sliding. 3. Touch feeling is softer compared with plastic white keys. The distinctive pattern and color of ivory keys also attracted many pianists. Recently however, only few pianos with ivory keys are produced due to the standpoints of animal and environmental protection. Yamaha sought to implement white keys with the similar touch to ivory keys, and they accomplished to produce artificial ivory-like white keys called "New Ivory" in 1985. However, the problem was that the New Ivory easily absorbed sweat and finger marks, which induced yellowish white keys. In response to this, Yamaha decided to change the material for the improved New Ivory keys in order not to cause the excessive color change. The first model that the improved keys were attached was the New Ivory special model in early C series, manufactured from 1985 to 1990. For those pianos, Yamaha put "NI" stamps in the white keys. This "NI" stamp guarantee the quality of the keys, and also can prove that original Yamaha parts are attached to the piano. Yamaha's many experiments after the initial release of "New Ivory" made it to release the new ivory-like keys named "New Ivory II." Yamaha currently releases artificial ivory-like keys in the name of "Ivorite," the same name in the world since the current CX series. We have pianos with New Ivory or Ivorite keys in our stock. Please contact your staff for further information.