Concept

Die-deterioration doubling

Summary
Die deterioration doubling (DDD) is a common form of mint-made error on many United States and Canadian coins that results from degradation of the die used to strike the coin. Due to a combination of improper preparation and treatment of the dies, excessive wear, and overuse, die deterioration doubling has occurred on nearly every series issued by the US mint in recent times. Certain coins are more susceptible to it than others, due to various factors, but it does occur on most series of coins. Causes Annealing Errors During the annealing process of die making, two main errors can occur, resulting in less than perfect dies. It is impossible to tell without expensive and lengthy tests whether these errors occurred, but they will lead to significantly weaker dies and a higher tendency to deteriorate quickly. The first thing which can happen to a die in this process what metallurgists call decarburization. Decarburization is the result of an improper mix of metals a
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