A generic term applied to a mark on a coin from another coin; it may, or may not, have been incurred in a bag.
A surface mark or small nick acquired by a coin when it came in contact with other coins inside a mint bag. Bag marks are most common on large, heavy silver and gold coins.
A surface mark, usually in the form of a nick, acquired by a coin when it came into contact with others in a mint bag. Bag marks are most common on large and heavy silver and gold coins.
The hits and ticks on coins that were caused by contact with other coins. During the early years of minting, coins were ejected from the presses and into bins or bags along with many other coins. These bags were physically handled several times before reaching their final destination, causing the coins to hit each other and create lots of "bag-marks." Coins with the fewest bag-marks are obviously more valuable.