Thanks to all for your suggestions!! Here is a followup.
The ring has spent the folowing:
A couple of days in an egg white/yoke mix. . . no visible change (but the cleaning was 'interesting').
A couple of days in a baggy with an onion slice and a day with diced onion. . . no visible change.
Two days in a baggy filled with propane (refilled for the second day). . . . this time there was _some_ new tarnish.
Looks like the gas is the 'leader' but just wearing it may be just as fast .
I think the wife will see if the jeweller has some "liver of sulfur" next time she is in Silverdale.
Thanks again!!
Bob rgentry at oz dot net