If you were to take it to sea and leave it wet a lot of the time I'm sure it would eventually, but not on its own. It's very early in its journey, and the brass has just dulled slightly. It's a shame, I'd quite like a bit of green patina on it - maybe not quite that much tho.
If you read that thread, the owner of that watch used three or four chemical treatments to get his brass looking like that. Not sure its possible naturally.
tempted. not sure I'll like the brass on wrist though. will it end up looking like this ?