As promised I tried lasering terracotta, am I IMPRESSED worked first go, no pre treatment just a cleaning with a dry cloth.
PNG image using 2W diode laser 95% power and 1000 speed, Greyscale.
This one was the base of a terracotta mosquito coil holder, which I already had and just wiped the inside with a dry rag. I imagine using terracotta pot saucers in future.