Dispersion Staining is a means of rapidly determining the refractive index of a particle by imparting characteristic colors to colorless objects. The technique is based on the difference between refractive index dispersions of the particulate solid and liquid medium in which the solids are immersed.
Biological microscopists routinely use chemical stains and dye-stuffs to aid their identifications of tissue, bacteria, and cell structures in their preparations.
Microscopists who deal mainly with inorganic materials are not so fortunate. They find that it is usually difficult or impossible to chemically color-stain their preparations as a means of distinguishing between various phases or structures of interest. However, there is a way. By making use of the Christiansen effect, it becomes possible to optically impose characteristic colors onto the boarders of colorless microscopic particles.