You can send it to Perry Null in Gallup, NM. I have heard on here that they do a great job. Check out this post.Perry Null Trading Repairs I don’t have the address handy, but I bet someone on here does, or you can Google it.
And I am no jewelry fixing expert, but I believe water could loosen the stone in the setting and cause it to fall out (if it’s native made anyway). We have had discussions on here about not leaving your rings on while washing your hands.