The results of optical absorption measurements on potassium colloids in KCl crystals have been presented in this paper. The samples were annealed at various temperatures with different time. It is found that the colloids band is dependent on the annealing temperature and annealing time. The transformation process between F-centers and colloidal centers were observed. The colloids band shows complex structures for the samples which did not attained equilibrium, indicating that there are different kinds of colloidal centers in such samples. Also we found that in these samples(which is in the nonequilibrium state), the transformation process from F-centers to colloidal centers does not stop even at room temperature.