Eileen, for lots of advice on this, go through the Orchid Archives,
looking for Prismacolor on Copper.
If you have access to jewelry magazines, see the articles in
Lapidary Journal Jewelry Artist, August 2004, p. 21ff.
Art Jewelry Nov. 2008, p. 30ff.
Art Jewelry, July 2010, pp. 42-48
Google Prismacolor on Copper and the references there.