A die gouge, often simply dubbed a gouge, is a raised feature on a coin's surface resulting from the coin's dies having been nicked by a tool, piece of metal, or other hard object to cause an indentation.
Die gouges are often created during the working life of a die. This results with two or more die varieties coming from the same die. In the VAM world, the original variety is given a digit VAM number and the varieties with the gouge(s) are given that same number followed by a letter. This categorization process is the same for die progressions involving pitting, clashing, die polishing, or any other alteration during the die's working life.
The biggest die gouge celebrity is the 1890-CC VAM-4 "tailbar," which has a pronounced gouge below the eagle's right tailfeathers. This variety apparently had the die gouge from the first coin struck, so it therefore is considered the mother die of the variety and does not have the additional letter designation.
A die gouge is distinct from a die crack or die break, which is caused by the natural deterioration of the die. These cracks often appear in and around the peripheral devices. While die cracks progress over time and become longer and/or wider, die gouges remain the same from inception to the retirement of the die.
The King of the die gouges is the 1894-S VAM-1A with over 45 die scratches/gouges on the obverse. Most on a Morgan dollar obverse die.
Additional die gouge varieties of recent interest are the 1888-S VAM-13, the 2006 VAM of the year, and the 1891-S VAM-8A, with the longest related die gouges in the Morgan series. The largest obverse die gouge can be seen on the 1878-S VAM-19. The longest die gouge of any 1921-D variety is 1921-D VAM-1U. Other notable die gouge variety are the "Hangnail" 1880-O VAM-48 and the "Thornhead" series 1921-S VAM-1B.