I've been unsuccessfully trying to identify this mark. The late owner traveled quite a bit--although she was from the USA, this ring probably isn't. It's likely mid-to-late 20th century, and apparently needs a cleaning. Maybe that's a "18 CI" and not "18 CT" and out of the scope of this board. :) I'd love assistance or guidance in how to search. Thanks!
(Sorry about the size!)
