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<p>[QUOTE=&quot;Skyman, post: 2520899, member: 28299&quot;]As in many things in life, it is not a black and white answer.&nbsp; To a large extent it is something you pick up over time, by learning what a given Type/Date/MM generally looks like.&nbsp; If you can, go to local coin shows, even small local ones will, over time, give you a large enough internal database to be able to discriminate between artificial toning (AT) and natural toning (NT).&nbsp; You will find that AT generally falls within 3 categories, moving across the spectrum of &quot;real&quot; toning; blatant AT, market acceptable toning (MA), and indistinguishable toning.&nbsp; One of the key tip-offs is the color progression.</p><p><br /></p><p>Colors on a coin are caused by the same physical process that occurs when you see gasoline showing rainbow colors on a water puddle.&nbsp; The process is called Thin Film Interference. The colors seen from a thin film are a function of four things: the color of the coin&#039;s surface, chemicals (if any) on the coins surface, the thin film interference effect and the inherent color of the thin film. As most transparent or translucent thin films grow thicker, they will become black. The inherent color of the thin film will have an effect on the shade and tint of the thin film interference effect.</p><p><br /></p><p>The primary color progression for silver (this means silver colored surfaces, so cupper/nickel US alloy applies here) is as follows:</p><p><br /></p><p><b>No toning - Light Gold - Banana Yellow - Burgundy - Dark Blue - Light Blue - Silver - Lemon Yellow - Red - Blue - Green - Yellow - Red - Green .... Black</b></p><p><br /></p><p>The primary color progression for copper (actually means copper colored surfaces) is as follows:</p><p><br /></p><p><b>No toning - Orange (Red copper color) - Burgundy - Dark Blue - Light Blue - Silver - Lemon Yellow - Red - Blue - Green - Yellow - Red - Green .... Black</b></p><p><br /></p><p>Please note that the colors <b>&lt;Yellow - Red - Green&gt;</b> keep repeating- becoming grayer after each repeat until it turns black.</p><p><br /></p><p>Oftentimes a blatantly AT&#039;ed coin will be blotchy, as opposed to showing a reasonably consistent transition from one color to another.</p><p><br /></p><p>Another &quot;test&quot; is whether there is color differentiation between higher and lower parts on the devices of a given coin.&nbsp; For example, on naturally toned Morgans you will generally see a difference in the color of the hair of Liberty depending on whether the hair is relatively higher or lower on the planchet, e.g. the crevices will show a different color than the top of the hair.&nbsp; If toning chemicals have been applied as a liquid to the coin, then these crevices will show the same toning as the upper parts of the devices.</p><p><br /></p><p>As mentioned, AT toning can also be market acceptable (MA) toning.&nbsp; What this means is that the TPG grader suspects the toning is AT, BUT the toning is close enough to the &quot;real&quot; thing that they will slab the coin.&nbsp; For example, this summer at the ANA I saw a 1956 Franklin half dollar that was slabbed MS67FBL.&nbsp; I have specialized in collecting Franklins for almost 30 years now.&nbsp; The coin was accurately technically graded.&nbsp; The toning was ALSO something that was quite reasonable for a Franklin.&nbsp; The kicker was that the toning was the sort of toning that would be quite common on a D mint Franklin from 1957 or 1958.&nbsp; It was NOT the sort of toning that I have EVER seen on a P mint from 1956.</p><p><br /></p><p>Finally, of course, you get to the AT toning that is indistinguishable from NT.&nbsp; By definition, you cannot tell that it is AT.&nbsp; One possible issue of some of these sort of coins is that after you buy them, given that the color was created by accelerated means, the coin can continue to tone at an accelerated rate after being slabbed, and progress all the way to the tertiary tone, e.g. black.</p><p><br /></p><p>One other point, some blatantly AT coins are quite attractive.&nbsp; Each person has to decide whether they will buy AT coins or not.&nbsp; I am perfectly willing to buy them, AS LONG AS I am NOT paying a significant toning premium, and as long as the coin is a &quot;common&quot; coin, for example say a 1922 Peace dollar in MS62. </p><p><br /></p><p>I will be the first to admit that differentiating between AT and NT is a messy process.&nbsp; I strongly suspect that some of the coins in my collection that I believe are NT are in fact AT.&nbsp; I also strongly suspect that I have turned down buying attractively toned NT coins, thinking that they are AT.&nbsp; The best one can do is to try and minimize the amount of AT coins that one has.&nbsp; This also gives you a greater appreciation for the true rarity and beauty of NT coins.[/QUOTE]</p><p><br /></p>

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