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<p>[QUOTE=&quot;Burton Strauss III, post: 2565867, member: 59677&quot;]Specific gravity is (if you&#039;ll pardon the pun) the gold standard test.</p><p><br /></p><p>The ice cube and magnet tests are less direct, they depend on characteristics of silver not present to the same extent in the base metals used in counterfeits.</p><p><br /></p><p>For example, silver is a good conductor of heat (better than copper, or gold, especially better than tin and zinc)</p><p><br /></p><p>German silver (used for many contemporary counterfeits) is an alloy of copper, nickel and zinc, which conducts heat about 1/20th as well as pure silver (Interestingly worse than any of it&#039;s components).</p><p><a href="http://www.engineersedge.com/properties_of_metals.htm" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.engineersedge.com/properties_of_metals.htm" rel="nofollow">http://www.engineersedge.com/properties_of_metals.htm</a></p><p><br /></p><p>But the lab measurements are done by applying heat to the face of a smooth bar and measuring the temperature rise at the other end - which we can&#039;t do for a coin.</p><p><br /></p><p>With the ice cube test you are doing an indirect measurement - how well heat is conducted from the (rough) face through the (rough) reverse and into whatever heat sink the coin/bar is sitting on.</p><p><br /></p><p>That&#039;s why it&#039;s best done in parallel - two bars resting on the same heat sink, two ice cubes. If the melt time is significantly different or substantially the same, they are different or same composition (could, of course BOTH be counterfeit).[/QUOTE]</p><p><br /></p>

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