It is composed of natural mica wrapping rutile Titania. The color can be changed by precisely controlling the wrapping thickness of Titania. As the thickness grows, the color can be changed into gold, red, purple, blue and green in turn which is fairly similar to the rainbow interference color. It is an optics phenomenon. The optical path difference between the reflex of Titania with high refraction index and of mica with low refraction index intervenes with each other and produces different colors.