Very nice old ring, ihan.
It was presumably made in one (of three) country in the Kingdom of Yugoslavia between 1918 and 1943.
Maybe the original owner had been a soldier in the second World War?
It has indications of 2 methods of craftsmanship on or in it- ring was made in the 'lost wax' method and was then engraved by hand.
It might help to have it weighed & its' purity tested at a jewelers, to establish the rings' minimum value.
