Hub Trials and Die Trials are usually uniface (struck on one side) impressions using either the obverse or reverse die. These Die Trials can be from finished or unfinished dies. These are deliberate strikes to test a certain design or example. Sometimes hubs are used, rather than the actual finished die.
Metals other than the adopted composition are frequently used to strike hub trials and die trials. They are sometimes struck in copper and white metal. Other times they are struck in softer metals like tin or lead. There are even some examples struck in wax and on cardboard.
These trial strikes are listed in the 8th Edition of Judd and also in Pollock. Technically hub trials and die trials are part of the pattern family. However, in the last 5 years the coin market has drastically changed directions.
Many pattern enthusiasts have always wanted a hub trial or a die trial piece to go along with the specific type or denomination of pattern(s) that they collect. A new demand has emerged for hub trials, die trials and splashers. Collectors of major mint errors are placing these in their collections becuase they are unusual, exotic and unique.
Even though they are not mint errors, they are aggressively sought after by people who collect off-metals, broadstrikes, uniface strikes and coins struck on larger planchets. In addition, since many of these hub trials, die trials and splashers are struck from incomplete hubs and dies, the design may be only a partial portrait or with parts of the legend and date missing.
There is something really special about holding a die trial gold piece struck in copper that is also uniface or on a larger planchet.