I went into a jacuzzi wearing a sterling silver necklace and it turned BROWN! I had warn this necklace for 4 years and this had never happened before! Here's how I fixed it:
~Take a pot deep enough to submerge what your trying to fix.
~Line the pot with aluminum foil.
~Add 1tsp of salt and 1tsp of baking soda
~Add enough water to cover the object
~Bring to a boil and "cook" for at least 3 minutes!
~It was a bit dull afterward so I cleaned it with toothpaste and it's good as new!!