Ladies Sterling Silver Oval Gray Moonstone (?) Ring Size 6

Nice ladies silver ring in a size 6. This is stamped sterling on the band. I am not a jeweler so I am not sure what the center stone is but it looks like moonstone. If I am not correct, please message me so I can change the listing. There is a patten number on the ring and the number 5. It looks to have scratches on the band from normal wear. Please see all photos as they are part of the description.