Keneth, Advise your client that at no time should she (or he)
subject gold to bleach (chlorine) at any time for whatever purpose.
That includes swimming pools with chlorine disinfectant, washing
clothes, etc. Chlorine attacks gold alloys and causes a condition
called Chloride stress corrosion. This results in weakening of the
metal and eventual breakage and is the cause of many lost stones. As
for the green cast,I don't know. Doesn't sound too good. I would try
sanding and repolishing but wouldn't have much faith in the remaining
strength of the metal.
Jerry in Kodiak