The first United States pattern coins were first struck at the Philadelphia Mint in its established year of 1792. The purposes of pattern pieces were to test concepts in different dies and metals while other patterns were designed for collectors. Each pattern piece was assigned a Judd number (e.g. J-1234) by numismatist J. Hewitt Judd, M.D. in his guide, United States Pattern, Experimental, and Trial Pieces. There are no true price guides for pattern coins. Pattern experts estimate prices and collectors look at records of what different pieces last traded for at certain auctions. Grading of patterns can sometimes vary widely between certification services and pattern experts. There can be a mintage of only 1 to just over 1,250 for each pattern. Pattern coins are a rarity of the U.S. Mint.