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<p>[QUOTE=&quot;TypeCoin971793, post: 2645233, member: 78244&quot;]Original surfaces on a circulated 100+ year-old silver coin will be an even grey usually with a lighter greay (called &quot;circulation cameo&quot;) on the higher points of the devices, like this quarter:</p><p><br /></p><p>[ATTACH=full]584231[/ATTACH] </p><p><br /></p><p>Yes, in circulation, the patina (H2S bonded to the silver to form Ag2S) does wear off, creating a light pale silvery color like on the relatively-modern silver coins you see in the junk bins. However, 200 years of sitting around in a high-sulfur environment (remember: these coins sat through the industrial revolution, where tons of sulfur were pumped into the air every day), so they almost always toned this way. </p><p><br /></p><p>The &quot;dark residue&quot; you speak of is actually the previous layer of patina. Notice how there is a dark halo around all of the devices. This is sometimes due to grime buildup in the crevaces, but if the fields are significantly lighter, that means the main part of the patina was stripped away (aka cleaning) while leaving the patina in the hard-to-reach areas. A harsh, vigorous cleaning will get rid of the patina in these crevaces, but that is not the case here.</p><p><br /></p><p>The wild colors on toned AU and Uncirculated coins is caused by a phenomenon called &quot;Thin Film Interference.&quot; You can read about it in my article here: <a href="http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=186193" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=186193" rel="nofollow">http://www.coincommunity.com/forum/topic.asp?TOPIC_ID=186193</a></p><p><br /></p><p>Note that coins that grade less than AU-55 should <i>not</i> have rainbow toning with the exception of residual luster in grades as low as VF-35. These can be discerned by color appearing very tightly around the devices. I&#039;ll upload a couple pictures of coins like this shortly.</p><p><br /></p><p><br /></p><p><br /></p><p>In terms of detecting a cleaned coin, the &quot;look&quot; is not at all subjective. It is a matter of fact that is repeated very consistently delending on the coin&#039;s history. The glossiness comes from an attempt to shine up the metal. Wear from circulation and a thick (&gt;1000nm) patina will greatly dull the surface of a coin. When this patina is removed and some friction is used to &quot;polish up&quot; the coin a bit, the surfaces get a little bit of an unnatural shine for the grade. There is a large difference in the appearance of the OP coin and the Bust Dollar. Look at the two side-by-side and note the differences.</p><p><br /></p><p>That being said, the Bust Dollar has also had a cleaning, though it was much older and less abrasive than the one the half had. Compare it to my quarter. Notice the paleness to the surface. If left alone for 200 years, it would look like my quarter. However, when cleaned, the surface resets itself and begins retoning. This coin has been retoning for a very long time, and it looks attractive, even if it is not 100% original. Look through a bin of &quot;junk&quot; 90% quarters and halves and you&#039;ll see coins in various stages of the retoning process after being taken from circulation.</p><p><br /></p><p><br /></p><p><br /></p><p>That quarter is perfectly original. You say it isn&#039;t shiny in hand. That is the look you should go for in an EF 100+ year-old coin.</p><p><br /></p><p><br /></p><p><br /></p><p>Every coin has a patina (with the exception of many gold coins due to the lack of reactivity of gold), with some having a thicker layer than others. There is also the dirt and grime aspect as well, as [USER=24254]@crypto79[/USER] points out.[/QUOTE]</p><p><br /></p>

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