One more note as reread the thread. there is also a ranking to the metals used.
None
Brass
Silver
Gold
Gold with enameling
If I remember right there was actually an old court decree that specified which rank you had to be before you could wear each - course I got that from a museum guide at the Royal Palace and can't confirm, however he was adamant about the fact that gold with enameling was reserved for members of the royal family.
I have a gold ring that has my unit's crest on it, I used to have the same ring in silver, but when I became an Officer my wife insisted that I had to give it to my son and wear a gold one now
Dan