Vintage Signed S Sterling Silver Oval Mood Ring Size 6

Oval mood ring with a silver band. Features a color-changing stone. Since it is old and in my possession I have not seen the pattern changed too much, so I’m not sure if it is stuck like this or will continue to vary a little bit. I have not tested this as sterling silver (don’t have the testing kit), but it is engraved with an S on the back as shown. I can wear a 6–7 on my ring finger and this fit snug, so probably a 6.