Just made a couple samples for an upcoming job. It’s 3/8″ clear plate with what’s called a “chiseled edge”, or sometimes a “chipped edge”, or most often a “scalloped edge”. There are special tools (not a chisel) designed specifically for this effect. I don’t have the special tool so here’s proof you don’t necessarily have to have it.
It’s important to finish the edge to the point it is 100% safe to touch. This of course means using your own hand to thoroughly test it when you think it’s finished.