good info above, and no there is not any markings as such, but that being said, there are two "extremes" to keep in mind,,,,one if a gun looks TOO good to be true, or is being touted as "brand new, never fired" , little lights should go off in your head, especially if there is BIG BUCKS involved, the other side ,or end of the extreme is , if a gun looks like it was reblued, then it most likely was........comparing one , to another is kinda tough as there are so many reasons for two guns to be quite "different" looking, storage, cleaning/maintenance, chemicals and solutions used, and how hard one rubs and wipes...also time,, exposure to sun light, makes two guns look totally different from one another, also, the light you are using, and what is on the gun , (oil or wax?) etc...........
I know of quite a few shops, and gunsmiths, who can make ANY old Ruger look "as good as new" and in MANY cases, BETTER......Rugers' factory finish is NOT at or near the top of the heap in desired and quality final finish, compared to Colt or S&W, as well as today , the bluing formulas are NOT even close to any of the older , blues ( nitre).....been there ,done that. :roll: :wink:
Good luck, and if any questions, good pictures "may" help,but I can tell you , with digital photos and the internet , one can make a sows ear ,into a gold purse.......I for one have to "see, touch, inspect", in person to make any proper , intelligent answer. 8)