I have gotten very nice, cherry to burgundy red patina on copper by
using heat. Just flux the piece, heat it until it glows dull red, keep
it hot for a few seconds. The copper will at this point look black.
Thow the pieceinto water (not pickle!) while it is still hot, the
black oxides will come off and leave the copper an attractive red. In
fact, I made a bola slide with silver overlay on copper and achieved
this effect by simply dropping the piece into water instead of pickle
after the final soldering. I made that piece appoxmately a year ago
and the color of the copper remains unchanged, despite the fact that I
did not treat the finished piece.
Hope this helps!
Lee