Besides color and composition, particle size matters when it comes to choosing pigments. The reason is that particle size dictates the luster and reflection of a mica. In general, higher particle size means more sparkle but less coverage. Below is a summary.
Lastly, it is worth noting that natural mica pigments with a particle size of 150µm and more are not recommended to use on face and not allowed near eye area. Other applications do not have this particle size restriction. However, synthetic mica is not subject to this restriction.