The origin of this mysterious Pattern has never been explained. The dies are plainly those produced by the Royal Mint, London, in 1827 for the mint at Guanajuato (see lot 413). Here a reverse die, which must never have been lettered, has been cut from quite a different font for the Hermosillo mint, 1882, with the initials J. A. The initials, and the style of font, are appropriate for Hermosillo at this date, so that the piece was presumably struck there.