If your ring was your Great Grandmothers I would imagine it is quite old, likely causing some fading making the markings on the inside of the ring more difficult to read. Sometimes as you describe, you will see just the word "silver" on a piece of jewelry, but more usually you will read "Sterling Silver" or .925. These markings can be very difficult to spot, so use a magnifying glass or a jewelers loupe to get a close-up view. Hope this helps.
