I have had this for quite awhile. It is unlike all other fully unplated or partial-plated cents I own. Notice how blue it is and that it has luster. Has anyone else seen any this color blue before? Is it even a genuine unplated cent? I see faint copper, in particular around the rim. Also, ANACS gave this an MS65 (older white holder)...not so sure it should get that high, especially with such soft details on the reverse. Makes me wonder if this was altered...
Interesting question, but I've been led to believe that there isn't any luster under the copper layer -- that the flow lines don't get impressed that deeply. I don't know of any accessible ways to strip off copper without attacking zinc, but I understand that it's possible. If I could manage one of those methods, I'd start looking for Zincolns from very late-stage dies (deep and coarse flow lines), and see for myself what's under there.
Joe, that one looks good to me, from the photos. However, don't assume every Unplated Zinc Cent in an ANACS holder is genuine - there are good quantities of them out there in the old white small holders that have been de-plated. When they first came out, ANACS assumed they were all mint releases - took a year or two to have some genuine ones show up, and we could then compare them to the de-plated examples. (which are darker, of course)
Weight is meaningless in this situation, imo. The plating weighs nothing, and with scale and tolerance issues, I've never used a scale to determine authenticity of these unplated cents.