From royal scandals to Depression-era street games, these ridges have seen some stuff
You’d think that after spending decades on this planet—most of those using money—I’d have a handle on pocket change. But yesterday, while cleaning out the bottom of a junk drawer, I found a half-dollar coin. My first thought? Score! Now I can buy … well, not much these days. A half of a candy bar … on clearance? But as I stared at the coin longer, I found myself wondering, Why does this tiny disco pancake have ridges on the edges? Why have I never noticed this before? Do all coins have ridges?
And just like that, I abandoned the junk drawer in favor of diving down an internet rabbit hole. Were the coin ridges there for grip? Decoration? To foil counterfeiters? To make them look fancier than they actually are?
Turns out, there’s a fascinating reason behind this design choice—and it’s about way more than just aesthetics, says Louis Davern, a numismatist (that’s a coin expert, not someone who reads minds for spare change) and coin historian. “The ridges started for one important historical reason,” he says, “but have since become integral to the ‘fabric’ of modern coins for many other reasons.”
Curious? Me too! So buckle up, fellow loose-change ponderers, and read on. Your piggy bank has secrets to spill!
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Did coins always have ridges?
Nope! In fact, the very first coins that we know of—thought to have been minted around 600 BCE in the ancient kingdom of Lydia (now modern-day Turkey)—were pretty basic. Think smooth-edged blobs made from electrum, a naturally occurring mix of gold and silver, that looked more like rejected chocolate coins than currency.
As coins evolved, particularly in ancient Greece and Rome, they were stamped with intricate images and came in standardized shapes, but they still didn’t have those telltale ridges. Ridges weren’t introduced as a design feature until the late 1500s, Davern says—because some devious thieves realized the smooth edges could be exploited. Yes, they found a way to literally make more money out of money.
Why do coins have ridges?
Coin ridges were invented to combat a sneaky little trick called coin clipping. This was basically the 17th-century version of skimming from the till: Clever criminals would shave small amounts of precious metal off the edges of coins, then spend the lighter coins at full value while melting down the trimmings to sell, Davern explains. “Without other coins of reference, this fraud could be hard for the authorities to identify,” he says.
To stop this currency corruption, Sir Isaac Newton—yes, the apple guy—stepped in. As Master of the Royal Mint in England during the late 1600s, he introduced milled edges (those ridges!) to make tampering obvious.
“The ridges were added as an anti-forgery and anti-clipping measure,” Davern says. “The introduction of milled edges made it easier for the authorities and the public to identify clipping, as the clipped edge was smooth rather than milled.”
It worked so well that the idea crossed the pond and was adopted by the U.S. Mint when it started producing coins in 1792, where it became standard for coins made of precious metals.
Why do only certain coins have ridges?
Dimes, quarters, half-dollars and some dollars have ridged edges, while pennies and nickels do not—and the answer has to do with what the coins are made of and how much they’re worth. Because, as it turns out, not all coins are worth the effort.
“The extra cost of creating coins with milled edges isn’t worth it on some base metal coins,” Davern says. “No one will clip the edge off of them, as the base metal is simply not valuable enough to warrant doing so.”
Basically, coins made from valuable metals, like silver or gold, got milled edges to prevent people from shaving off slivers. But coins made from cheaper metals, like copper or nickel, aren’t worth enough to tempt would-be clippers. Pennies and nickels never contained enough valuable metal to be worth clipping, so they didn’t need the anti-theft bling.
Today, however, coins are no longer made from those fancy materials (sorry, coin collectors), but we’ve kept the ridges on higher-denomination coins out of tradition and for continued security, since it still makes them more difficult to counterfeit, Davern adds.
Do those ridges have an official name?
Coin ridges are officially called a “reeded edge” or “reeding” in the U.S. and a “milled edge” or “milling” in the U.K., Davern says.
It’s one of those fun numismatic terms that most people have never heard, but once you know it, you’ll never forget it! So go ahead and drop that term casually into your next conversation. You’re welcome.
How are those ridges created?
Coin ridges aren’t carved in by tiny elves with chisels, though that would be adorable. They’re actually formed during the striking process at the mint.
Here’s how it works: A blank metal disc, called a planchet, is placed into a machine between two dies (which stamp the coin’s design), while a third piece called a collar surrounds it. That collar has grooves in it, and when the coin is struck, the pressure forces the metal into the grooves—creating the ridges.
Each reeded coin has a specific number of ridges:
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A dime has 118 ridges.
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A quarter has 119.
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A half-dollar has 150.
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A Gold or Silver American Eagle has 198.
And no, there won’t be a pop quiz, but feel free to use that info to dominate at trivia night.
Why do coins still have those ridges today?
Ridges aren’t used on every coin or in every currency, but they’re pretty common around the globe. “Milled or reeded coins have been used worldwide to combat clipping and fakes,” Davern explains. And even though modern coins don’t contain precious metals anymore, ridges still serve several important purposes.
Security
“Milling is no longer as useful for combating fakes, as the technology of forgers has advanced,” says Davern. “Now we use other technologies to protect against fakes, like holograms on coins.” Some countries, like the U.K., have even taken ridges to the next level. In 2017, Britain ditched its old round £1 coin and replaced it with a 12-sided version that’s much harder to counterfeit. (Because if there’s anything coin forgers hate more than reeding, it’s geometry.)
Touch ID
Ridges help visually impaired individuals distinguish between coins of similar size. For instance, a dime is smaller than a penny, but the ridges give it away immediately by touch.
Tradition
Let’s be real: Coins just feel more official with ridges. As Davern puts it, “milling is part of the fabric of coins.” It’s what people expect to see—and feel—on legitimate currency.
Automated sorting
Vending machines and coin-counting devices use the ridges, along with other physical characteristics, to identify and validate coins.
Aesthetics
No, #coinaesthetics isn’t the next TikTok trend (yet!), but coin designers take a lot of pride in their work, including the edges. Reeding makes the coin look more finished and gives it a little flair.
Better grip
One surprising perk of those ridged edges was discovered during the Great Depression, when folks would pass the time (and try to win a little cash) by pitching coins toward a building wall. The goal was to get your coin to land closest to the wall, and savvy players quickly realized that reeded-edge coins, like dimes and quarters, gave them better control during the toss. Today, the ridges still make them easier to pick up, especially if you’re trying to wiggle a coin out of that little pocket on your jeans.
Emergency emery board
So this isn’t an official reason, but it is very handy! I snagged a nail cleaning out that junk drawer and used the ridged edge of the half-dollar to file down my fingernail a little bit. It totally worked!
Are those ridges here to stay?
Most likely, at least for as long as metal coins stay in circulation. (The penny has already been decommissioned, and rumor has it the nickel will soon be.) While digital payments are becoming more common and the future of physical currency is uncertain, there’s currently no major movement to remove reeded edges.
And Davern is honest about their diminishing practicality: “Clipping stopped being a problem when we stopped using precious metals in our day-to-day coinage.” And since forgers have upgraded their tools, ridges alone won’t stop modern fakes. But they do add to the aesthetic of the coins, and “milling will be used for the foreseeable future,” he says.
Still, the next time you find a quarter wedged in your couch cushions or stuck in your car’s cupholder, take a second to admire those little ridges. And then maybe use it to file off a ragged edge on your fingernail. Now, if you’ll excuse me, I need to finish cleaning out that junk drawer!
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Sources:
- Louis Davern, numismatist, coin historian and head of auctions at The Coin Cabinet; online interview, Aug. 5, 2025
- Timothy S. Y. Lam Museum of Anthropology: “Ancient Coins: Make Your Own Money!”
- APMEX: “How Many Ridges are on U.S. Coins?”
- United States Mint: “The History of U.S. Circulating Coins”
