One thing that I failed to mention is that both of the coins had apparently identical weight according to the auction descriptions. I didn't weight mine, but the auction it came out of said it was 3.68g and the suspected original was 3.69g. Mine was sold in 2009 and the original (if it is indeed the same coin) was sold at auction in 2005.
If tooled by laser, magic, or the Dark Side Force in a way that it removed material, I wonder if the weight would change appreciably? Alternatively, having it virtually the same weight in my mind adds further evidence supporting that it is the same coin. Wouldn't it be very difficult to replicate the weight in a cast?
Btw, Lloyd, thank you very much for your education explanation on lost wax casting! Very much appreciated. I did not know how it is done.
In looking at the
weights of the two(?) coins the difference is within the accuracy of low cost electronic
scales which at typically read plus/minu 0.015 gm (despite claims to the contary). Thus the same coin weighed on different
scales could be expected to vary in measured
weight by up to 0.03 gms.
Tooling of the coin (by any means) would remove metal and thus lower
weight, but this is likely to be within the error
bar attached to the measurement on different
scales.
A metal
cast with shrink volumetrically on cooling around 0.5% - 1% for pure silver if my recall is correct, more for other alloys (
http://en.wikipedia.org/wiki/Pattern_%28casting%29 ) so all other things being equal (which of course they are not) the volume shrinkage will translate into a
weight reduction compared to the master which would be measurable, but on a 3.69 g coin the
weight reduction in the
cast would be of the order of 0.03-0.05 gm so noticable if weighed on the same
scales, but more difficult to detect if the coins are weighed on different
scales (other than high precision scientifc
scales).
A better test for the
cast volumetric shrinkage is the actual dimensional measurement of the coin, rather than
weight. The volumentric shrinkage is readily measured with a vernier
caliper, but of course one has to have the two coins, master and
cast side by
side to to the comparitve dimensional measurements.
So my hunch is that the
weight difference you see recorded is of uncertain significance, unless you can confirm that the
weights were recorded on either the same
scales at the same time, or using scientific precision
scales rather than the low cost digitial
scales used my most people/dealers.
Fake Coins and Notorious Fake Sellers
