Co‐Al2O3composites were prepared by dual electron beam evaporation. When the volume fraction of cobalt is lower than 0.07, the metal is almost completely dispersed as ions in the amorphous oxide matrix. Due to the local ordering of amorphous aluminum oxide, absorption bands caused by crystal field effects are seen in the visible wavelength range. The features of the spectra are consistent with cobalt ions located in tetrahedrally coordinated sites in the oxide. Thus optical absorption measurements can be used to determine whether the metal is present as ions or as particles in various cermet materials.