Same for the 4x4s I get. I did a couple of hundred of them for a reunion.
The 4x4s usually have 3 sides that are unglazed with one side where the glaze wraps over half or more of the side thickness. None of the sides have tile setting tabs.
I color the sides with an oil paint Sharpie - either black or color matching the coloring I applied to the engrave. Takes just a few moments to slide a wide/chisel tipped one along the edge.