Found ring at thrift store and need info?

Bought it for only 1 dollar so even if it doesnt have value, i will not have lost much. So anyhow, i believe that the diamond on it is real, there are roman numerals vii engraved on the inside, and it seems to be plated. The metal under the plating is also silver colored, but opaque. All i can conclude is that the roman numerals stand for a 7 yr anniversary, but if the diamond is in fact real, why would the ring be plated? Any info on any of the qs will be greatly apreciated. And i will take it to a jewler that i know, but have to wait til tuesday.