Bought this one thinking it is a N-23 R-5. Looks to be f-15 to vf-20ish Am I right? https://www.ebay.com/itm/1847-Braid...qYnkmlSQgU%3D&orig_cvip=true&nordt=true&rt=nc Might get a closer look on original listing
IMO VF 25-30. Wish I could help you out on whether it's a N-23 but I don't know the diagnostics. More experienced members can probably help you out on this.
An expert copper restorer / preservation person might be able to remove the greenish stuff from the obverse safely. You might try to push it around with a toothpick or something like that to see if it moves. I would be concerned that it might dig into the surface if it has not already.
Just asking out of curiosity. How much value does Newcomb numbers, in general, add to Large cents. I don't see many Braided Hair Large cents on ebay with N numbers.
Not nearly as much as some of the asking prices on ebay. According to my CQR it probably adds about $10 to $20 over a more common coin. Someone who collects the rarer die varieties would be the most interested I suppose. It is fun to try and find them unattributed.
There aren't a lot of people trying to collect die variety sets of late date cents so with the exception of the very rare varieties there isn't usually much premium. For the most part anything less than an R-5 will not bring a premium and many of the the R-5's don't bring much premium unless they have a low condition census. For example your N-23 shows the lower end of the CC as an XF-40 for the 15th finest known and the guides don't show a premium until that level. The 1847 N-36 also an R-5 has the 15th finest is a F-15 and it shows a high premium for a VF-20 (Lowest grade shown in the guide for late dates.) Another reason you don't see many listed with Newcomb numbers is because attributing late dates is not easy, especially in coins that grade less than VF-XF.