Re: Pre or post mint?
- A few more points.
Examination of a coin under a microscope is sometimes helpful in
detecting plating jobs. Microscopic gaps sometimes can be seen and
these reveal the underlying metal.
Some people claim to be able to detect a plated coin by sight alone.
Heavy electroplating is readily detected by virtue of the mushy-
looking design elements. However, thin deposits might not be so
easily detected. There are other ways to plate coins as well. "Wash
plating" is hard to detect. Here coins are immersed in a solution
saturated with metal ions itching to attach themselves to the nearest
I have seen numerous plating jobs that are so convincing that I have
been unable to distinguish them from the real thing.
Apart from the "scratch test" applied to the edge of a coin, one can
sometimes also use a specific gravity test or a test of electrical
conductivity to distinguish real from bogus coins.
As I mentioned before, weight is an unreliable indicator. I have a
1965 Columbia 2 centavos with two layers of plating -- nickel and
over that, brass (I think). Yet, the coin weighs LESS than all the
normal coins I used for comparison. The coin managed to perplex
several well-known collectors. I resolved the problem with
the "scratch test".
> Shallow scratches sometimes don't penetrate thick plating. Sincethe
> coin is already worn and scratched, I would scrape the edge of theable
> coin against a very fine-grained sharpening stone. Give it a good
> hard scrape. Then examine the edge under a 10X lens. You'll be
> to tell if there's copper under the silver-colored surface.Well, I got permission from the owner to test the rim of the coin. He
> Natrually, I would not recommend this procedure for an uncirculated
said "go for it". Here are the results:
- That's certainly definitive. You went through the zinc plating that
was applied outside the mint, then through the copper plating, and
down to the zinc core.
Sometimes invasive methods are the simplest and most direct way to
solve a mystery. You have proven my point that plated coins are not
necessarily heavier than a normal coin.
> Well, I got permission from the owner to test the rim of the coin.
> said "go for it". Here are the results:
- Jason's case of a zinc-plated cent reminds me of
another coin in my collection. I bought a beautifully struck,
uncirculated, apparently unplated zinc cent with a dark gray
coloration. At first I thought it was a normal cent that was zinc
plated outside the mint because it was slightly overweight (2.52
grams) and the surface was marked with a few microscopic bubbles
I didn't pay much for the coin, so I scraped the edge against a fine-
grained sharpening stone. Believe me, I gave it a good, hard
scrape. Lo and behold, no copper lay beneath the surface. It turned
out to be legit. I can only assume that the planchet itself was
slightly overweight, and the scattered bubbles were created by some
step in processing. The copper plating could not have been
chemically stripped off outside the mint. If this had been the case,
the surface would show some roughness and the design features would
be a little mushy.
It just goes to show you how tricky some of these errors can be.
--- In errorcoininformationexchange@y..., "dermestid" <mdia1@a...>
> That's certainly definitive. You went through the zinc platingthat
> was applied outside the mint, then through the copper plating, andnot
> down to the zinc core.
> Sometimes invasive methods are the simplest and most direct way to
> solve a mystery. You have proven my point that plated coins are
> necessarily heavier than a normal coin.coin.
> > Well, I got permission from the owner to test the rim of the
> > said "go for it". Here are the results:
> > http://home.pacifier.com/~craton/plated.JPG
> > Jason