Every "pigment" added to the base material contains metal ions. The application of the laser changes the crystal structure of the metal ions and the amount of hydration in the crystal. This causes a chemical change in the composition of the pigment component, resulting in a concentration of the pigment and a change in color.
A chemical change involves the change in a substance through chemical reactions. The chemical reactants form a new product with equal mass. The following is a list of evidence that can indicate that a chemical change took place.