The reeded edge of a coin is the series of grooved lines that encircle the perimeter of some U.S. coins, such as the dime, quarter and half dollar. If you inspect other coins, you will see that some of them don't have any reeding on the edge of the coin. Additionally, you may find coins that have words or symbols on the edge. Regardless of what adorns the edge of a coin, it's there for a purpose.
How Do the Reeds Get on the Edge of the Coin?
Those small grooves that you find on the edge of a coin are usually added during the striking process. Coin dies produce the obverse and the reverse of the coin. To hold the coin securely during the striking process, a metal collar that is the exact diameter of the finished coin is placed in between the two coin dies. At the United States Mint, the collar is only 1/5000 of an inch wider than the diameter of the coin die. This very tight tolerance forces the metal during the strike into the deepest recesses of the coin die instead of squishing out the side. A planchet is placed on top of the anvil die and held securely by the collar.
The collar has a series of small grooves carved into it around the entire circumference. When the planchet is struck at enormous pressure, the metal in the coin tries to expand out the side but is held in place by the collar. The tiny grooves on the collar are now transferred to the edge of the coin.
Another method used to impart reeding and other edge adornments are to strike the coin first and then put it through a milling machine which will add the reeds or different designs to the edge of the coin. This process is ordinarily done by rolling and squeezing the coin in between two metal strips that have the grooves or other design engraved on them. The Presidential dollar series coins produced for circulation use this method for imparting the incuse edge lettering on the coin.
Why Do They Put Reeds on the Edge of a Coin?
Originally, minting facilities made coins out of precious metals such as gold and silver. As coins circulated, unscrupulous people would use a knife or file to scrape off a little bit of metal from each coin they handled. As hundreds or even thousands of people shaved off a small amount of precious metal, the coin would get smaller and be worth less than its stated value.
In colonial times, merchants used to weigh the coins that people were using to purchase goods. If they were underweight, then the merchant would ask for some additional coins to make up the difference. To stop this practice of shaving or "clipping" coins, mints around the world added adornments such as reeds, lettering or some other type of decorative devices. If the edge adornments were gone, then you knew someone had clipped the coin and reduce the amount of precious metal in the coin.
In 1696, Isaac Newton became the warden of the Royal Mint in the United Kingdom. He chose to implement reeded edges on coins to prevent clippers and counterfeiters from tampering with the currency.
What Are Other Types of Edges on Coins?
Although there is no definitive list of the different type of edges on coins, here are a few of the most common (and some uncommon) edges you will find on coins:
- Plain: The edge is smooth with no indentations or design on it.
- Reeded: A series of small grooves running perpendicular that encompass the entire edge of the coin.
- Lettered: Letters can be relief or incuse into the edge of the coin. They may contain complete words, abbreviations and/or symbols.
- Grooved: This edge contains a groove that runs parallel to the surface of the coin and circumnavigates the entire edge of the coin. At first glance, this may look as if there are two coins glued together.
- Interrupted Reeded: A series of reeds followed by an equal space of plane or unadorned edge. This pattern repeats on the entire edge of the coin.
- Indented: A series of indentations equally spaced around the edge of the coin. This is found on some euro coins, like the 20 cent euro.
- Herringbone: A series of crisscrossed tiny grooves that form a shape that resembles interconnected arrows and encompass the entire edge of the coin.
- Serrated: A series of grooves that form a V shape on the edge of the coin. It continues evenly around the entire circumference of the coin.
- Slant Reeded: A series of grooves that are slanted across the edge of the coin. Very similar to reeded edges, but the grooves are slanted. This type of reading cannot be applied to the coin during the striking process.
- Center Reeded: These grooves on the edge of the coin do not extend completely across the coin's edge. They are limited to the center of the edge. This is another example of an edge of adornment that must be applied after the coin is struck.