The Ridges That Guard A Coin’s Third Side
Turn a coin sideways and you may find a row of narrow grooves around its edge. These grooves are called reeds, and the patterned surface is known as a reeded edge. Reeding began as a practical defense against theft. It later became part of coin design, manufacturing, identification, and quality control. The edge is sometimes described as a coin’s third side because it can carry features separate from either face.