I put up a thread a couple weeks ago about leaving my Michael Valitutti Ethiopian Opal in soapy mild jewelry cleaner for a month. It turned grayish yellow. I reasoned mine was water-logged, so I put it in a very low oven, maybe 130 degrees, for a few hours. In my case it worked, but since yours was in salt water, not plain water, I wouldn't suggest it. Since you bought it from JTV, you might call them and see if one of their GIA trained people can advise you. Or email them and cross your fingers. If that doesn't work, try to find a gemologist in one of your local jewelry stores.
I JUST READ JTV GEM TREATMENT GUIDE ABOVE AND IT SAYS AVOID HEAT, SO DON'T DO WHAT I DID, I was just lucky. I would have salvaged the russian chrome diopsides if my cure hadn't worked.