Chalcedony - but what doe the markings mean?

[LCS]

I've had this ring for years. I got it at a resale shop and just always wondered about its origin, as well as the markings. I'm fairly sure it is chalcedony - but will say the setting seems very heavy. Even though the unusual shape does not make one think it, it is very comfortable and allows for a second ring to be worn on my ring finger. Any comments on the markings?