Why Do Dimes Have Ridges on Their Rims?
You have probably noticed the ridges, or grooves, on the edges of such U.S. coins as dimes, quarters and half-dollars. At one time, high-value coins were made of silver and gold.
Dishonest people sometimes cheated by trimming some of the valuable metal off the edges of coins.
This lowered the coins’ value. To prevent this practice, coin makers began putting ridges called “reeding” on the coins’ edges, so trimmed coins could be easily detected.
The reeded edges also made coin design more intricate and counterfeiting more difficult. Coins are no longer made of precious metals, but dimes, quarters and half-dollars are still minted with ridges.
Aside from keeping up with tradition, the ridges also help make the coins distinguishable from each other by feel as well as appearance, enabling visually impaired people to tell the difference between similarly sized coins, like the dime and penny.