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<p>[QUOTE="TypeCoin971793, post: 3244255, member: 78244"]<b>Step 2: Look at the Color:</b></p><p><br /></p><p>This step is the one I use the most when I try to determine if a coin is cleaned. The trick here is to know what a coin is supposed to look like in a specific grade. Any deviation from that expectation should be looked upon with scrutiny.</p><p><br /></p><p>Important Notes on color for Original Coins:</p><p><br /></p><ul> <li>Silver tones naturally, and the presence or absence of luster determines color</li> <li>Lustrous coins usually have rainbow toning when they are toned.</li> <li>Circulated coins have dull medium to dark gray toning, with exception of many post-1916 coins because any accumulated patina was continuously rubbed off in circulation. Pre-1878 coins were subjected to highly-sulfurous air from the industrial revolution which caused accelerated toning when they were pulled out of circulation. The air quality was much better after 1964 when the “junk” silver was pulled out of circulation, so they didn’t tone as quickly, which is why the coins in “junk” silver bins are not darkly toned.</li> <li>Copper naturally tones from red to brown, despite the presence of luster. Lustrous “brown” cents can have rainbow toning.</li> <li>Some copper coins have a “wood-grain” texture from alloy-mixing issues.</li> <li>Gold normally does not tone (though there are exceptions because of alloy mixes), so this section can be ignored with respect to gold coins.</li> </ul><p>Again, I use that “luster” word again. Why is it important here? The answer is that coin luster has a reflectivity that circulated coins do not have. When light waves hit a lustrous part of the coin, the light is reflected off of the coin instead of being absorbed by the metal. When this happens through a patina (or “toning”), a phenomenon called thin film interference occurs, resulting in a rainbow of colors on a coin’s surface. When the light is absorbed by the metal, you don’t get thin film interference and you get a dull grey or brown color, depending on the metal.</p><p><br /></p><p>An original lustrous UNC coin:</p><p><br /></p><p>[ATTACH=full]850001[/ATTACH]</p><p><br /></p><p>An original EF coin:</p><p><br /></p><p>[ATTACH=full]850002[/ATTACH]</p><p><br /></p><p>Older coins toned because they were pulled out of circulation and set aside during a time of lots of dirty industry, so there was lots of sulfur in the air. Every time a coin sat somewhere for an extended period of time, it would quickly try to patinate until it would be wiped off when the coin was spent. Larger coins were often hoarded and not spent because of their large buying power, so repatination was easy. This was less common with smaller denominations minted after the Civil War. When a coin was spent, there was a little rubbing on the high points that wiped the patina off these areas, making the patina on the high points thinner and thus a lighter grey because it absorbed less light. This is called a “circulation cameo”, and it is often a good sign of originality.</p><p><br /></p><p>Color on circulated coins is not always a bad thing. As stated earlier, luster is present on the upper circulated grades. This luster is key for rainbow toning to form, so where there is luster on a circulated coin, there can be rainbow toning. Notice how on the below examples that where the luster ends, the rainbow toning also abruptly ends.</p><p><br /></p><p>[ATTACH=full]850003[/ATTACH]</p><p><br /></p><p>[ATTACH=full]850004[/ATTACH]</p><p><br /></p><p>Here is an original copper coin with a nice brown color.</p><p><br /></p><p>[ATTACH=full]850006[/ATTACH]</p><p><br /></p><p>And here is an example of a copper coin with a woodgrain coloring</p><p><br /></p><p>[ATTACH=full]850007[/ATTACH][/QUOTE]</p><p><br /></p>
[QUOTE="TypeCoin971793, post: 3244255, member: 78244"][B]Step 2: Look at the Color:[/B] This step is the one I use the most when I try to determine if a coin is cleaned. The trick here is to know what a coin is supposed to look like in a specific grade. Any deviation from that expectation should be looked upon with scrutiny. Important Notes on color for Original Coins: [LIST] [*]Silver tones naturally, and the presence or absence of luster determines color [*]Lustrous coins usually have rainbow toning when they are toned. [*]Circulated coins have dull medium to dark gray toning, with exception of many post-1916 coins because any accumulated patina was continuously rubbed off in circulation. Pre-1878 coins were subjected to highly-sulfurous air from the industrial revolution which caused accelerated toning when they were pulled out of circulation. The air quality was much better after 1964 when the “junk” silver was pulled out of circulation, so they didn’t tone as quickly, which is why the coins in “junk” silver bins are not darkly toned. [*]Copper naturally tones from red to brown, despite the presence of luster. Lustrous “brown” cents can have rainbow toning. [*]Some copper coins have a “wood-grain” texture from alloy-mixing issues. [*]Gold normally does not tone (though there are exceptions because of alloy mixes), so this section can be ignored with respect to gold coins. [/LIST] Again, I use that “luster” word again. Why is it important here? The answer is that coin luster has a reflectivity that circulated coins do not have. When light waves hit a lustrous part of the coin, the light is reflected off of the coin instead of being absorbed by the metal. When this happens through a patina (or “toning”), a phenomenon called thin film interference occurs, resulting in a rainbow of colors on a coin’s surface. When the light is absorbed by the metal, you don’t get thin film interference and you get a dull grey or brown color, depending on the metal. An original lustrous UNC coin: [ATTACH=full]850001[/ATTACH] An original EF coin: [ATTACH=full]850002[/ATTACH] Older coins toned because they were pulled out of circulation and set aside during a time of lots of dirty industry, so there was lots of sulfur in the air. Every time a coin sat somewhere for an extended period of time, it would quickly try to patinate until it would be wiped off when the coin was spent. Larger coins were often hoarded and not spent because of their large buying power, so repatination was easy. This was less common with smaller denominations minted after the Civil War. When a coin was spent, there was a little rubbing on the high points that wiped the patina off these areas, making the patina on the high points thinner and thus a lighter grey because it absorbed less light. This is called a “circulation cameo”, and it is often a good sign of originality. Color on circulated coins is not always a bad thing. As stated earlier, luster is present on the upper circulated grades. This luster is key for rainbow toning to form, so where there is luster on a circulated coin, there can be rainbow toning. Notice how on the below examples that where the luster ends, the rainbow toning also abruptly ends. [ATTACH=full]850003[/ATTACH] [ATTACH=full]850004[/ATTACH] Here is an original copper coin with a nice brown color. [ATTACH=full]850006[/ATTACH] And here is an example of a copper coin with a woodgrain coloring [ATTACH=full]850007[/ATTACH][/QUOTE]
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