And, not really being a badge person, but I think that they started being worn from 1917 onwards (hey. just like the motto!)
Yes, polished, but by far and away not the most polished one I've seen. I once saw an example of about 7 or 8 stages of the manufacture of one of these, going from the flan to the strike to the cutting out of the badge.
It certainly gave you a whole new respect for the production of a fairly common item...