My dad's friend had a story like that... he found a (man's) ring on the bathroom sink at a casino, with a big expensive jewel in it. His theory was someone took it off to wash their hands, and forgot to put it back on. Being a practical man, he let the staff know he had found "a ring", and told them if anyone came looking for it and could describe it to him he'd promptly return it to them, but he would not be handing it over to the relatively-low-wage staff behind the front desk. He was there for another several days, and checked back repeatedly, but no one claimed it.
So he kept it, and wore the ring for ten years.
Finally, on another vacation to Vegas, he took the ring off to wash his hands in the bathroom, and accidentally walked out without it. Moments later he rushed back, but it was gone. He didn't bother inquiring if anyone had found it, he figured it was just time for the ring to move on.
