I do not think this gun has been refinished. It is a 19 made in the 80's isn't it? Is it a round butt? I believe you have a Conn. State Police or the US State Department gun which were contract guns often with no additional markings but were done in matte blue. They were 2.5" 19s.
Search the S&W forum and you will find many references to them! I believe your sweet deal is even sweeter than you initially thought.
It appears to have a smooth target trigger. Is that the case because if it does that would be consistent with the CT guns.