The gnomish contraption before you bears a plaque calling it "The Sparklematic 5200".  The gist of the machine, from reading the instructions below the plaque, is to scrub away dirt that an item might have.  The machine has a coin slot, accepting three silver coins to start the process once the item is placed inside it.$B$BIt would seem as though the grime-encrusted ring you found earlier is just the thing to try in this machine!