Why Do Some Coins Have Tiny Ridges Around Their Edges?

The ridges around a coin may feel decorative, but they began as protection against people quietly stealing precious metal.

For much of history, coins were made from valuable metals such as silver and gold. Their stated value was connected to the amount of metal they contained. A dishonest person could shave a narrow strip from the edge of several coins, collect the fragments, and spend the altered coins at their original value.

This practice was called coin clipping. It could be difficult to notice because early handmade coins were not always perfectly round or identical in size.

Mints responded by creating carefully formed edges. Parallel grooves, known as reeding, made any missing metal more obvious. Some coins received lettering or decorative patterns instead. A clipped section would interrupt the design and reveal that the coin had been altered.

Modern circulating coins are generally not worth their face value because of precious metal content, but the edge patterns remain useful. They help people distinguish coins by touch and make denominations easier to identify when their sizes are similar. Reeded edges are particularly valuable to people with limited vision.

Different edges can also assist vending machines and other coin handling equipment, although weight, diameter, thickness, and electrical properties may be more important to modern sensors.

American pennies and nickels have smooth edges, while dimes and quarters are reeded. The difference preserves a visual and physical tradition that survived long after clipping stopped being profitable.

Those tiny ridges are therefore traces of an old struggle between mints trying to guarantee a coin's value and people attempting to remove that value one invisible shaving at a time.