Polychrome is a term to define a tourmaline that has several colors merging in the stone such as we see here a mixture of red and green. This stone has a natural uncut raw face and areas of that it has been polished smooth. Tourmaline has all the hues of color from black to white going through the entire spectrum: white, yellow, orange, pink, red, indigo, teal, violet, purple, brown, black. Tourmaline is one of the few stones that presents a pzyzoeletric propertiy, just like quartz crystal This means that the stone can translate mechanical stimulation into electrical charge and vise-versa. ( More information on this on Kendra Grace's book, "Aromatherapy, Crystals and Vibrational Healing", pg 145. In consideration of the complexity of this stone composition, it finds a synergy best with an oil of the simplest composition that has a full spectrum influence: Sandalwood.