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Message:: [QUOTE="physics-fan3.14, post: 4289595, member: 19165"]I've used the word "chatoyance" to describe the effect of luster for many years (although some argue with my use of the term). It doesn't have anything to do with die polish, however - its all about the metal flow. As the coin is struck, the metal tends to flow radially outward from the center. These flow lines are what we see as luster. However, some coins have basin shapes (the curvature of their fields) which are not uniform. Or, because of the shape or relief of the coins, the metal flows unevenly. On a low relief coin, or a coin with a shallow basin, you'll tend to see a single cartwheel. However, on something like the Mercury reverse (with both a high relief and a high basin), you'll get multiple pinwheels instead of a single cartwheel. You'll notice something similar on the Buffalo nickel as well. As far as I understand your question, [USER=69760]@iPen[/USER] , the effect you are asking about has nothing to do with ghosting. The apparent "ghost" image of the other side appearing occurs late in the life of a die. However, the pinwheel effect occurs throughout the life of the die and is a result of the design of the coin.[/QUOTE]