Why do some coins have ridges?
New styles of edge markings have been used to replace or augment traditional reeding. For example, some coins have “interrupted” reeding, featuring alternating bands of smooth and reeded metal, while others have thick reeds that resemble worn-down gear teeth. EU 2ยข coins even have a groove running laterally around the edge, a bit like an Oreo cookie, rather than reeds oriented vertically with respect to the coin’s faces.
