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<p>[QUOTE=&quot;desertgem, post: 3220439, member: 15199&quot;]If you do not know the alloy material&nbsp; and percentage the rest of the coin is made from, you have a mess.&nbsp; For example </p><p><br /></p><p>( quote) : Different alloying elements have different SG&#039;s, e.g., 8.90 for cobalt and nickel, 8.94 g/cc for copper, 10.49 for silver, 12.0 for palladium, 12.4 for rhodium, 21.45 for platinum, etc.<span style="color: #ff8000"> It is possible for alloys of different gold concentrations to have same SG, and for alloys of same SG to have different gold content. An alloy of 83 vol.% platinum and 17 vol. % copper will have roughly the same SG as 100% gold. </span>Even knowing the composition (wt.% or at.%) of a multi-component alloy, it is difficult to accurately calculate the exact SG because non-ideal thermodynamic interaction of atoms will affect the volume. Porosity is another problem.&quot; </p><p><br /></p><p>you can find data for simple alloys such as gold-silver and gold-copper. But because of multicomponent effects noted above, 9 carat gold has SG range 10.9-12.7, <span style="color: #00b3b3">18 carat yellow gold 15.2-15.9, 18 carat white gold 14.7-16.9</span>, 22 carat 17.7-17.8, sterling silver 10.2-10.3.</p><p><br /></p><p><a href="https://www.finishing.com/189/07.shtml" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.finishing.com/189/07.shtml" rel="nofollow">https://www.finishing.com/189/07.shtml</a></p><p><br /></p><p>You need to have a component analysis before the s.g. is calculated and compared. Maybe someplace there is an analysis of mining sites where the gold for the coin came from, but often that is not possible.&nbsp; If you can find the process that the author in post 1 used to determine the part on carats of hyperpyrons used to do sp.gr. and repeat it , would be a fair guess. IMO , Jim[/QUOTE]</p><p><br /></p>

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