Simplest and just as reliable is a sharp steel scriber. Pick a mark you
can reproduce and pull the scriber (rather than pushing like you do a
pencil). I've yet to find a surface too hard to mark (but diamond
scribers are cheap these days if you need something harder). Doesn't
really matter what the pattern is as long as it's unique. I got the idea
from an old rancher in eastern Oregon that marked all his tools with his
registered brand, using a nail. Made sense to me.

Another possibility is a sharp steel punch. I've still got a few of my
grandfather's tools and they're all marked with a unique four dot
pattern. But a scribe is easier on a round surface.

The real advantage is it's quick and available, so you can mark your
tools when you get them. I find if I need something more complex I tend
to put it off and forget to do it.

Jim