A method for the quality control of a cosmetic composition changing its electromagnetic spectral properties under application conditions from an initial state to an end state. The composition is subjected to a measurement condition under which the change of electromagnetic spectral properties occurs over time, the change of electromagnetic spectral properties is measured at least at two different points in time, where the electromagnetic spectral properties at an earlier point in time are different from the electromagnetic spectral properties at the later point in time and at least one value of a parameter derivable from the measured change of electromagnetic spectral properties is determined and compared to a control value of the same parameter.
