Ceramic materials are extremely interesting for the use in energy technology due to their resistance to steam and pressure. In many cases, their application requires precisely structured surfaces, which can be realised, for example, by precise ablation with nanosecond-pulsed lasers. The present work shows some new insights into the surface grooving of high-purity aluminium oxide surfaces by nanosecond laser processing. In the light of preliminary tests, 3D diagrams of laser ablation depth, laser beam scanning speed and the number of laser passes at selected pulse repetition frequencies were obtained. It was found that the surfaces of diagrams are remarkably twisted and cannot be explicated by the Chryssolouris’ linearity. Based on the experimental results, a theoretical model for controlled pulsed laser ablation was established, emphasising the importance of laser absorptivity for vaporisation (rather than laser fluences). The physical relevance and magnitude of laser absorptivity for vaporisation are discussed.