Take pearlescent pigments as an example, pearlescent pigments are a class of pigments with pearl luster, which are deposited on the substrate (generally natural mica, synthetic mica, glass sheet and other sheet-like materials) above a layer or alternately deposited multiple layers of metal oxides or non-metallic oxides and formed a flat sandwich body with a structure similar to sandwich. Due to the difference in refractive index between the substrate and the oxide deposited on its surface and each oxide, when the light shines on the surface of the pearlescent pigment, the incident light will be refracted and reflected at the interface of each layer of the pearlescent pigment, and the color of the pearlescent pigment that people see is the result of the superposition of light after multiple refractions and reflections of the light, that is, the interference phenomenon of light.

Mica is a new non-metallic crystal material, a national key new material, with heat insulation, insulation, high temperature resistance characteristics, is an important material in aerospace, rail transit, nuclear power, wind power, aircraft carriers and other high-tech fields, but also electrical equipment, wire and cable, household appliances indispensable insulation material, in the national economy and national defense construction plays an important role.