Unlike sink in a washing bin, I don't have access to the U shape part of the pipe and it's not visible. What is the recommended way to get the ring? The ring is quite heavy and not magnetic; I'm have doubts that wet vacuum can do it.
“Curse us and crush us, my precious is lost!”
Perhaps a -
for your phone and a wire bent into a hook ?
If it’s in the P-trap, you can suck it out with a wet-vac.
Try watching in with a tooth mirror and a flashlight, if you can see it that way, use a hook shaped piece of iron yarn and hook it. Otherwise I think hiring a plumber is the best option (if the ring is valuable)