Unknown silver ring. Maybe days stirWling <NRL>

I've found a ring. I have no information on it besides I found it while cleaning my grandparents house & No one knows where it came from. Its engraved on the inside of the band "Sterling" with either a W or a S in the middle of the word, followed by NRL or MRL inside of a horizontal diamond shape with the number 6 at the end, which I assume 6 is the ring size because my ring finger is a 7 & its just a tad too small for my finger. Ill post the best pictures I could get. Any help figuring out what this is would be appreciated. If nothing else, its pretty & kinda cool.