This is almost a IMHO:
On which finger would an unmarried (American) woman customarily wear a ring that wasn’t an engagement ring?
Backstory: My gf’s birthday is coming up and, for various fairly irrelevant reasons, we both think that a Celtic themed ring would work well. We’ve been together awhile and the ring would carry an implicit message of “we’re serious,” but we don’t want to commit a faux pas.
I’m sure this topic has come up previously, but my google fu is weak today (can’t find the right keywords).