Can anyone tell me about this ring?

[Bev]

I found this ring deep in the ground at a school yard. The school isnt old (60's) but the land is old farm land. The finish is really tough and almost looks like pewter. The red "stone" actually is more like a piece of stained glass. Someone told me that it could be a class ring but I can't see anything to prove that except for the shape. It's a women's size 6
The only visible mark is on the inside and looks like a raised "O" seen in the pic.
It's making me nuts. Even if I just found out what decade it could have been made or what was the name of the style used a glass center like this, I'd be somewhat satisfied.
Thank you

 

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[bluehunter1973]

old costume jewelry maybe? might have to get jeweler opinion

 

[Breezie]

Bev, Judging by the style, your ring looks to be from the late 40s-1950s. I know you said pewter, but from the pics it looks more gold colored. Is it heavy? Does it attract a magnet? Having a colored synthetic stone was not unusual for costume jewelry. I found a gold plated ring with a red synthetic stone. Here's the link:
http://forum.treasurenet.com/index.php?topic=294203.msg2118988#msg2118988
I always enjoy finding jewelry. Neat find Breezie