In my ongoing quest to see what I can laser, I tried doing my household logo in porcelain tile - specifically, this was a marble-looking backsplash 12x3" tile I got at Home Depot for a couple of bucks.
It took a while, since I wanted it to really engrave. Settings: speed 250, laser full strength engrave. I’d covered the tile with blue painter tape to keep it from scorching, but the tape charred around the edges. Right after taking it out of the GF, I thought the edges were going to be a problem, but five minutes of energetic scrubbing with a kitchen scritchy cleaned it right up. There’s definitely enough engraving depth to put paint into and wipe off the surface, but my girlfriend liked the gray look as-is. It’s not quite as mottled looking as in the photo here (which was taken in low light). I’m pretty happy with the result and am going to continue to engrave porcelain tile with different things.