I have learned that next time I need to do a much deeper etch, as the layer of enamel left over after stoning was way too thin, showing he copper underneath in places - not good. (See the brooch on the left - at the top). I will also use slightly thicker copper in the future.
On the bright side - the colours are nice, I like the designs, and I see potential in this technique.
Here is an example of how the red brooch looks before and after oxidising the copper:
I didn't do a last firing on these to re-glaze the enamel - because I could already see the enamel was too thin and would probably have burnt out.
But - this was a good exercise - there is so much to learn!
On to the next one...