In the past, people used coins made of precious metals for trade. And the value of the coin was equal to the value of the metal from which it was made. Common coins usually contain more than 90% precious metal. And scammers used it for a long time: they grinded or cut the edges of the coins, and this area was filled with cheaper metal.
The solution to the problem was that they started applying inscriptions or patterns to the edges of the coins. It was pointless to cut something out of such coins, as it immediately caught the eye.
Today, ribbed coins are still produced. This is because people do not want to replace stamps that are already in production, and such coins look nicer and hold better in the hand.
Source: Ferra

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