1968-S Kennedy Half Dollar
Struck on 125 grain (8.1 gram) Magnetic Planchet
PCGS Proof 62
Ex Fred Weinberg Collection
UNIQUE
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There are many major mint errors known on Proof coins issued by the United States Mint–including off-centers, off-metals, double and multiple strikes, bonded coins, and mated coins–but this is the only one known struck on a magnetic planchet.
Over my 45 years dealing in major mint errors, I’ve never encountered another U.S. Proof mint error struck on a magnetic planchet. Error specialist Fred Weinberg, who had this in his personal collection for decades, sold it in 2024. He stated that “as far as I know, this is the only known U.S. Proof mint error on a magnetic planchet and it is fascinating!”
The pressure of the Kennedy Half Dollar Proof dies expanded the diameter of the 8.1 gram magnetic planchet to the diameter of a regular Kennedy Half.
Although authenticated and certified by PCGS as Proof 62, it is as struck. The magnetic planchet does not have the reflectivity of a regular polished Proof planchet, nor does the cameo portrait show on the obverse. It has the typical look and color of the few Mint State U.S. coins that are known to be struck on smaller magnetic washers.
It is amazing that this unique Proof rarity survived over half a century. Obviously this was an intentionally produced Proof mint error (a piece de caprice). This spectacular and enigmatic Proof Kennedy Half Dollar struck on a magnetic planchet is in a class by itself.
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