At first glance this looked like a typical rim ding but upon closer inspection you can see some struck-in metal associated with the rim loss. I'm guessing this is an unusual struck-in rim burr.
Quote: Given the number of folks with questions about error coins, I suspect opportunities will arise for you and your skills. Your contributions here alone have been incredibly useful, and we thank you!
Idea: Start a Youtube channel where you talk through coins that folks send you photos of (hi-res only) to examine (for a small fee). If the coin is interesting enough, you could have the owner send it in for a special "Under the Mike roscope" feature video.
Tough to say one way or the other after those picts. IMO You can see some of the color blending on the clad part of the edge and I can't imagine environmental exposure on a new coin would cover the entire surface like this. I think its a minor annealing issue with little if any premium. It has a nice look to it though.
Quote: Is it possible that it's a tapered planchet
Quote: Anything out of place around the edge?
The edge thickness and reeding look completely normal.
Besides being slightly underweight I can't explain the the weakness seen around the rim. Perhaps this clashing event jarred the die slightly out of place?
A pretty strong collar clash here with some interesting weakly struck rims. the coin weighs 11.15g so it is a little light but it seems like something else may be going on here.
Grabbed this coin because I am fond of these errors though I took a chance with some pretty bad photos in the listing. The seller wasn't an error expert but they knew they had something good so for $60 it wasn't a steal but still a good deal I think. These errors are awesome but on zinc planchets they can lack that wow factor which I feel happened on this particular coin. The second strike took out a lot of the design of the first strike. The second date is on the bottom left of the jacket but too faint to call it a "two date" coin unfortunately.
I picked up a 2001 in collar flipover double strike a couple years ago so I guess I have a set of sorts of 2001 in collar double strikes. http://goccf.com/t/429547&SearchTerms=flipover
The B and E of LIBERTY look pretty neat on the top of Lincolns head.