Duane, and George,
Johnson Matthey puts out "an introduction to platinum" "box" of
helpful on this subject, as well as finishing,
alloys, melting, setting, combining, stamping and handworking.
It is free in the trade, but you have to send away for it. Like
to the UK. Here's the address: Johnson Matthey, New Garden
House, 78 Hatton garden, London EC1N 8JP, England. The Phone is
011-071-269-8000 or you can fax them at 011-071-269-8133. Hope
this will help you all out. It definately is a very good
reference manual. I refer to it all the time.