I recently purchased a ring online. It has what appears to be an 830 hallmark, and from my research, it looks to be Danish circa 1960-70s. The seller listed the item as "Sterling Silver, Art Deco, 1940's" and described the hallmark as 800. I'm not sure which of us is wrong, but in any regard, it is terribly rusted and I need to clean it. I've looked at the different methods for cleaning silver and my questions are these: Does the foil and baking soda method matter or change if the silver is 800, 830 or of a higher grade (ie. Sterling)? Also, the ring's face patina looks much darker and rusted than the underside of the ring where the hallmark is, including the ring portion- they almost have a goldish tinge, plus the ring looks to have its own markings, not identifiable by any of the research I've done. Can anyone help me determine what the hallmarks possible are on inside of the ring itself, and what the best method for cleaning 800 or 830 silver is?
Thank you kindly for your help,