I'd need to see more pictures of the gun with close ups of the bluing. From the one picture you posted, I see polishing marks on the frame and a scuff near the front of the trigger that appears to have been blued over. S&W would not have done that. It may have been refinished at some point before you got it. That knocks down collector value completely and it becomes a shooter. If the finish is original, it would bring between $500 and $600 in my area...maybe more in other regions of the country.