"an under water geiger counter" Is your wife trying to track or kill you with a radioactive ring?
My daughter lost a hearing aid on our farm in the snow, they are $2,500.00 each! We got word out to a local metal detecting club and about 10 treasure hunters showed up. The hearing aid was found in the snowman. They asked if they could come back in the spring to investigate some hits.
The lake at the end of my block always has a few guys sweeping the beach and shallows for change, rings and at least one Rolex that I know of that swimmers have lost.
I hope they can find your ring.