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<p>[QUOTE=&quot;GDJMSP, post: 1801440, member: 112&quot;]It&#039;s pretty simple, and it&#039;s been explained many times. And to understand it you merely need to know what the process is.</p><p><br /></p><p>With Proofs, while the manufacturing method is very similar to that of making business strikes, it is still a different method. Proof planchets are polished before they are struck, business strike planchets are not polished. Proof dies are also polished, but they are polished to a much higher degree than business strike dies.</p><p><br /></p><p>The method for polishing dies, both Proof and business strike, is also simple. There is a machine that does it. There is a large zinc plate, a round disk about 10-12 inches in diameter. The zinc plate is attached to the machine and the machine spins the plate, very quickly. Above the plate the die is held in a press, when the press descends the flat face of the die is pushed against the face of the spinning zinc plate. But before that happens the face of the zinc plate is impregnated with a paste of diamond dust. In the first stage of polishing a course diamond paste is used. In each successive stage of polishing finer and finer grits of diamond dust are used. This results in a progressively finer polish polish being imparted to the face of the die. Until finally it is polished to a mirror like finish. But only Proof dies are polished to this mirror like finish stage, business strike dies are not.</p><p><br /></p><p>Regarding your second question, the coins themselves are never polished, the only things ever polished are the dies. Nothing is done to the coins after they have been struck. The reason you cannot see the any hairlines on Proof coins is because of the fineness of the diamond dust paste that was used to polish the dies. It works just like it does when you polish anything else to a high degree. You can&#039;t see any hairlines because they are so fine that they cannot be seen without high magnification.</p><p><br /></p><p>And the devices of a die are never polished, in fact quite the opposite is true. The devices have a rough finish and it is intentionally rough. It is this roughness of the devices that causes the cameo effect on a Proof coin. The roughness of the devices is created with one of several methods. In the old days they used to use an acid. They would take a die that had been hubbed and pour acid into the depressions of the devices. On a die the devices, legends, date, all of that are like holes, depressions, pressed down into the face of the die. The acid eats away at the metal of the depressions leaving behind a rough texture. A texture like very fine pebbles, pebbles so small that individual pebbles cannot be seen with the naked eye. </p><p><br /></p><p>So now when a Proof planchet is struck, you have the polished surface of the planchet, the polished surface of the die, and the rough texture of the devices on the die. The metal flows across the polished surfaces and is forced to retain its polished finish. The metal that flows into the depressions of the die meets the rough texture of the devices and is forced to take on that same rough texture. This rough texture is known as frost. So on the finished coin you have fields that are highly polished and devices with a rough texture, a frost. It is the contrast between these two very different finishes that creates the cameo effect.</p><p><br /></p><p>Now the reason that some Proof coins do not have the cameo effect is because as more and more coins are progressively struck the Proof die is progressively worn by the metal of the planchets flowing against it. And eventually this repeated metal flow wears the surface, the rough texture of the devices, smooth. This results in a Proof coin with no cameo effect and a slightly lessened mirror like finish on the fields.</p><p><br /></p><p>As to your last question, why such a thing cannot be replicated on a Proof coin after minting, well, to a degree it can be replicated. You can take a Proof coin that has no frost on the devices (these are known as brilliant Proofs) and artificially add frost to the devices. This is often enough to fool some collectors and dealers. But the artificial frost can be detected by those with the necessary experience to know it when they see it.</p><p><br /></p><p>With business strikes what you ask about cannot be done. That is because the luster of a business strike can only be created by the flowing of metal. Luster has unique qualities that cannot be replicated by any other means. And any disturbance of the luster is easily detected, by just about anybody.[/QUOTE]</p><p><br /></p>

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