You will not find a more unusual ring than this one. It is 925 sterling silver with a large cabochon amethyst on a hinged top that opens to reveal a place for a spy message or a poison pill/powder. Just like you would see in the old movies when some ones drink is being spiked. It is marked by the maker ERR along with a Mexican silver mark. It is a size 6 but could be made larger or smaller. It is in great condition for its age which I estimate to be from the 1920's or 1930's. I purchased this ring from an estate have owned it for over 30 years but due to the arthritis in my hands can no longer wear it.