1907 Ultra Thin Planchet Large Cent - Ideas?

It is amazing how often acid treated coins appear on ebay and forums. Mostly labeled as struck on foreign or thin planchets. Once you learn to recognize the type, they can be spotted a mile away. They all have that fuzzy detail look, are usually much thinner than a normal coin with surfaces that are somewhat pitted. If you search ebay with the word thin, several examples will always show up. I wish I could round them all up and bury them. I hate to think how much money people lost on these but we all have had some hard lessons, I guess some harder than others.

, pennysaver!

Diameters should be slightly smaller. They may just not have noticed. If acid was beaded up on the surface, rims would not be affected.

On the diameter question, I think you need to take surface area into account. There is an awful lot more Obv and Rev than there is edge. You would notice the effects (planchet thinning) sooner then you would on the edge (reduction in diameter).