This study was concerned with the evolution that occured during alpha alumina comminution (either polycrystalline or monocrystalline, doped or non-doped alpha alumina). Comminution of polycrystalline alumina shows that the evolution of the stresses detected through triboemission is not monotonic as a function of the duration of the mechanical treatment. These stresses and those measured through X-Ray broadening do not seem to be of the same origin. Triboemission signals transmitted by monocrystalline alumina are different, but the same evolution is observed through comminution. Besides, the evolution of stresses detected through X-Ray broadening is different. Doping of monocrystalline alpha alumina (30 ppm Cr3+) does not provoke any significant changes when compared to undoped alpha alumina, as regards evolution during the comminution process. On the other hand, the T.S.E.E. signal has practically disappeared for a 2000 ppm Cr3+ content, and the evolutions of the stresses detected through T.E. and X-Ray broadening seem to be more complex.