First, I doubt that is real sterling sliver. If it was, it does tarnish to a dull silver or black but not gold colored. If it is real SS there will be a mark on the ring like .97.
In either case seawater or salt water is a very strong oxidizing environment. Think rust and how fast something like steel rusts when exposed to salt water. Same here working on the sliver and other metals in the SS like copper, where the water and O2 is oxidizing them. So, in short, you have a "rusty" ring now
There are many others that can tarnish SS, like sulfur's, acids, Ammonia. In air sulfur is the big culprit. I will add if you are using dechlor for the water they will really make a mess of a SS ring due to the sulfur.
You can clean it but getting a silver or SS paste or solution cleaner. They are quite common. I have a jar of it just for that. You can also try baking soda and a tooth brush.