Great tip Dennis thank you.
I think I have managed to confuse everyone by asking too many questions in one post.
Firstly I want to make a headpin by sticking a piece of wire into a copperclay ammonite, i wondered if copper wire would hold up to the firing.

Secondly I'm looking for a wire to insert into porcelain clay that will fire up to 1200C, i use nichrome wire but it doesn't look very nice