Here are some of the Saxon variants, including the v-notch Or kokarden and the controversial serrated Saxon Kokarden on far right, which I feel are period as I have found several older helmets including a war bond helmet with this type.
Here is a set of Saxon Kokarden which were made of zinc:
I thought they were very uncommon, perhaps even fake. It was only recently that I found out they were more common than you may think and they came in different variations. Saxon Kokarden are the only ones that I have ever seen in zinc.
Another officer pair from one of my restorations:
These are not zinc.
It would appear, that the painting process begins with an all white kokarde then the other colours are added. The first colour for Prussian kokarden is black. John's kokarde has an olive green ring whereas this one is more like a 'hunter green", like we see at Christmas