The generation of Mn4+ in α-Al2O3:Mn3+ by soft X-ray exposure is demonstrated with a large dynamic range of the X-ray generated Mn4+ luminescence signal, indicating the potential use of α-Al2O3:Mn3+ for multilevel optical data storage. Samples with a range of Mn concentrations (0.05, 0.1, 0.2, 0.4, 0.6 and 1.2 atom%) were prepared via a facile combustion method and the sample with 0.4 atom% was found to display the highest luminescence intensity. The stored information can be read out via the R-lines (2E → 4A2) under ∼470 nm (4A2 → 4T2), or ∼630 nm (4A2 → 2T1) excitation with the latter being preferred since photobleaching is minimized. Interestingly, the Mn4+ valence state can be fully switched back to Mn3+ by blue light exposure (e.g., 462 nm laser diode). The stored information could be repeatedly written and erased, showing no significant deterioration over five consecutive cycles, with less than 5% uncertainty.