The Quiet Drama Hidden in a Coin’s Edge

The edge of a coin is usually something that people overlook. There are very few people who actually look at the edge of a coin and most of those are collectors and can tell you a lot about the coin from the edge.

Before the late 1600s, the edges of most coins were plain and smooth. The edges of these coins were easily subject to clipping. In this process, small slices of the silver in the edges of the coins were scraped off. These lightly weighted coins were then spent at face value. The clipping was invisible from the two faces of the coin. The loss of silver from the edges of the coins was gradually accumulated. The value of the currency was slowly decreased.

When he was Warden of the Royal Mint from 1696, Isaac Newton spent a great deal of time tracking down people to execute for crime, including several counterfeiters. He was Master of the Mint until his death in 1727. Newton’s biggest achievement at the Mint was the introduction of the milled edge – a thin band of fine, serrated ridges machined into the edges of all coins made at the Mint. A file would quickly score and damage such an edge, announcing the currency’s dilution to the eye.

The milled edge was developed by different countries in different ways. Some have reeding, i.e. parallel lines around the edge of the coin, others have had words milled into the edge, often legal announcements, or the titles of monarchs. The intricate designs made by the French for example are as significant as the obverse of the coin.

Today, coin auctioneers and collectors will pay close attention to the edge of a coin. Even a weakly struck rim, a single groove that has been smoothed, or a worn-off letter or two can tell more about a coin than its portrait.

The edge was designed to be tamper-evident. It has become the hardest part of a coin for forgers to fake over time.