Judd-44 is a very rare die trial of an 1814 Half Dollar struck in platinum. One of the known examples was defaced with a small P punched into the obverse a total of 33 times. The punching was done outside of the coining press, as evidenced by the bulges on the reverse opposite each of the punchmarks. In addition, the word "Platina" was hand-engraved into the reverse in cursive writing above the eagle's head. This particular example is the only J-44 confirmed to exist in collectors' hands. Effective October 2012, PCGS began designating this particular coin as J-44a to differentiate it from the example without the punchmarks and engraving.
A second J-44 is part of the National Numismatic Collection at the Smithsonian Institution. This example was not defaced, but it has a heavy and obvious test cut on the rim above the sixth and seventh stars.
A third J-44 is rumored to exist based on a reference by Walter Breen in a 1974 auction catalog, but the coin has neither been confirmed or seen since before 1974 (if Breen is correct).
Apart from this experiment, no platinum coins were ever struck by the U.S. Mint for use as a circulating medium. Russia used platinum to produce 3 Roubles from 1828-1845, on 6 Roubles from 1829 to 1845, and on 12 Roubles from 1830 to 1845. The 3 Roubles were made in large quantities, but many have been melted over the years. The 6 and 12 Roubles were all very rare to begin with and remain so today. Since then, the scarcity of platinum prevented it from being a viable coinage metal.
The two known examples of J-44 were both struck from the same dies used to produce the Overton 107 variety. Die state evidence places the manufacture of J-44 in 1814.