or נחושת בגימור מושחם
or נחושת בגימור עתיק

This may help:

This source in English shows what this oil-rubbed finish looks like
http://www.palomapewter.com/pdf/PalomaLiners.pdf
(page 2)
You'll also note that the "oil rubbed" copper finish is achieved by using aged copper

Then look at this Hebrew jewelry site here:
http://www.art-imp.com/search.asp?q=����� ������
I believe they DO have a similiar finish.

Since the context may be a luxurious look - you may choose the "antique" version.