You work in a grading room. The problem is: Why would anyone need to authenticate a coin simply from the edge? I can think of two reasons right off. Please help me think of some more.
One thing would be for those looking through rolls of coins for silver (50c, 25c, 10c) as it would be quicker than checking the dates. (Edit: probably not what you meant by authenticating though)
I suppose to make sure the reeding/edge lettering etc. is correct for the date. I know some of the morgan guys count reeding (maybe for VAMS)?
It's an area of the coin that counterfeiters probably pay the least attention to. Fields and design are more visible. Z
To confirm if the edge is correct for the particular coin and see if there are any other signs of it being a counterfeit. Possibly to determine the composition.
To make sure the edge type was correct for the coin being authenticated . . . a reeded edge on an 1815/2 half Dollar doesn't compute. To make sure a coin has not been altered at the rim . . . mintmark embossed through a hole drilled in the rim.
To see if Correct for mintage ie open or closed collar strikes check reeeding count (70-s half dollar a very scary fake didn’t have the correct reed count among other tells) also to check for rim filing Or other damage
"Why would anyone need to authenticate a coin simply from the edge?" Without looking at the rest of the coin...you got me.
Those are the two major reason I could think of. A third could possibly be to eliminate an S reverse being milled and fit into a 1894 obverse, (check at the edge of the reeds and obverse/reverse of coin for a seam). Unless this is something like verifying vines and bars large cents, etc.
Thanks, many I didn't think of right away. Here is an easy one. If the surfaces of the coin were really messed up by damage, extreme wear, polishing, etc. There is one more and it has been mentioned already. Reed counts. For example, many very rare coins in the Seated Liberty Series can be authenticated by their edge reeding.
Curved and elliptical clipped planchets come to mind. No belly-line or no reversal (clad coins) is no good...
I get your point but I think I'd say that a bit differently. What I mean is this - I find it hard to believe that absolutely none of the counterfeits for these do not have the correct number of reeds. Now I don't know that for a fact, but since it's so well known, it seems to me that at least some of them would have the correct number of reeds. Now the pattern of the reeds, the specific diagnostics of the reeds for a given date/mint might be easily identifiable to those with the knowledge. But the "reed count" might be correct - and the diagnostics incorrect.
Unfortunately, at this time, most of the fakes are so crude that I have not bothered to count their reeds. I'm going to bet that they use the same collar for every Morgan.
To see if the coin was a milled coin, or whether it was hammered or cast. Especially a concern with medieval coins. Milled coins will have a raised rim whereas hammered ones will not.
Things get a bit complicated with that. The first milled coins were made in France in 1643, and all subsequent French coins were milled. Now all other countries followed suit, but with some it was a hundred years later before they made milled coins. My point is you'd have to know when the specific country began using milled coins before looking at the edge could confirm or deny authenticity. And there really aren't all that many people who know that kind of stuff. But if you do happen to know it, then yes the edge can be used to confirm or deny authenticity.