1. The cladding used on US coinage was an invention by two chemists who gave their patent to the US Mint. The Mint Director at the time, Mrs. Mary Brooks, gave both individuals a special achievement award and both shared a $5000 cash award. Without this invention we would be without many wonderful errors having a cladding issue!
2. The 1983-S Proof set included the new copper-plated zinc cents, which had become standard issue for circulation. Since the multiple strikings required for Proof coin production tended to break through the copper plating, exposing the underlying zinc, the Proof cents received a double coating of their copper plating. This remains standard practice to the present day for all Proof cents.
3. Proof Coin Edge-Incused Lettering Process. The minting process used to manufacture the Presidential $1.00 proof quality Coins is a one-step coining process that allows the edge-lettering to appear in a consistent location on every proof coin. Using a three-piece collar, the edge-lettering on the proof coins is incused in the edge of the coin at the same time that the obverse and reverse designs are being struck onto the blank planchet. This method produces edge-incused lettering that will always appear right side up when the coin is showing its heads side. Furthermore, the location of the lettering will always be in the same location on the circumference of the coin with relation to the obverse and reverse designs. In addition, the proof coins will each bear a faint demarcation line where the three segments that make up the edge-lettering collar are joined.