I agree with what has been previously said, WWII airforce ring which might have held a picture of his wife. Awesome find!
I took my Tiger Shark out for a swim. It was so happy for that it found me this military ring. I spent about a week to clean it up. It was incrusted in stone. After getting it cleaned I seen something funny about the top. The top will swivel to the side. Don't know what was in the frame, maybe a picture or something. Can someone tell me what kind of ring it might be. Thank you... KEN
An old army capt. that I know thinks it is called an Army officers cap ring for a picture from WWII. Maybe... KEN
It's a locket ring. The guy would have had a picture of his girlfriend, or wife in it.