We studied the microscribing of Al2O3 ceramics by a diode-pumped Nd:YLF laser. The third harmonic of a Nd:YLF laser (λ=349nm) was used. The scribing characteristics such as groove width, groove depth and debris height were measured. By varying the focal position of the beam at fixed laser power, we observed three regions characterized by the color and the profile of the irradiated area. Region I was marked by high debris and black color due to thermal effects at the focusing position, Region II showed brown color and good scribing properties with low debris height at a slightly defocused position, and finally Region III was unchanged color (original white) but little scribing due to low power density at the defocused position. These results show that an optimum energy for scribing ceramics exists. Finally good scribing without color change may be possible by adjusting the irradiation energy.