A photoluminescence study saw a shift of emission from 1050 to 1300 nm before and after implantation, suggesting the transformation of the octahedrally coordinated Cr(III) ions to the tetrahedrally coordinated Cr(IV) ions. Most importantly, the novel oxygen-implanted material remains unchanged after 10 hours of annealing at 200 C indicating its stability, and thus potentially providing a step towards the application of solid-state lasers using chromium(IV) as active ions.