You can also identify rings by dropping them down wells—different rings fall down (or don't fall down) the wells in different ways—and identify wands by writing on the ground with them. Definitely hard to pick up any of that on your own, though.
I think you mean "sinks" instead of "wells" (there's at least one behavior in NetHack that's inspired by the name of the sink, and they were reputedly included in the game so that NetHack would contain "everything, including the kitchen sink").
Good catch, my mistake. Thanks.
You can also GET rings from sinks... if you know how.