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<p>[QUOTE=&quot;desertgem, post: 890264, member: 15199&quot;]<p style="text-align: left"><span style="color: #000000"></span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p> <p style="text-align: left"><span style="color: #000000">If you are referring to rainbow or brightly colored toning, yes, as those colors are produced by thin layer diffraction due to ( here is Doug&#039;s designation) ^^^^^^^ the flow lines peaks ( that are referred to as the cartwheel effect) The chemical reactions tend to be of a monocolor deposit, and on a worn coin where the flow lines are worn flat, will be grey to black depending on thickness. Without the &quot;peaks&quot;, to diffract the light into rainbow colors, that is what you will get. Also wear tends to remove the tarnish/toning and to find AU or EF coins brightly colored is wrong, except in areas of the coin where the flow lines were well protected.</span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p> <p style="text-align: left"><span style="color: #000000">Here is the best link I know about thin layer diffraction and rainbow type toning. Also read the thread links in the first posting.</span></p> <p style="text-align: left"><span style="color: #000000"><a href="http://forums.collectors.com/messageview.cfm?catid=26&amp;threadid=716279&amp;highlight_key=y&amp;keyword1=color&amp;keyword2=chart" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://forums.collectors.com/messageview.cfm?catid=26&amp;threadid=716279&amp;highlight_key=y&amp;keyword1=color&amp;keyword2=chart" rel="nofollow">http://forums.collectors.com/messageview.cfm?catid=26&amp;threadid=716279</a></span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p> <p style="text-align: left"><span style="color: #000000">I have this link bookmarked myself, sorry it is on a different forum.The color chart in the first posting is based on material in the other threads, and is worth printing out as so many use the wrong color sequence.</span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p> <p style="text-align: left"><span style="color: #000000">Jim</span></p> <p style="text-align: left"><span style="color: #000000"><br /></span></p><p>[/QUOTE]</p><p><br /></p>

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