Get the best deal on Multi Aura Crystal Pendants. Crystal healing therapy involves placing gemstones on the body to draw out negative energy. Proponents of this technique believe that crystals act as conduits for healing ? allowing positive, healing energy to flow into the body as negative, disease-causing energy flows out. Metal-coated crystals are natural crystals, such as quartz, whose surface has been coated with metal to give them an iridescent metallic sheen. Other names for crystals treated so include angel aura, flame aura, opal aura or rainbow quartz.