The ratios and purity of the coin metals varied considerably. Most Chinese coins were produced with a square hole in the middle. This was used to allow collections of coins to be threaded on a square rod so that the rough edges could be filed smooth, and then threaded on strings for ease of handling.

Why do coins have square holes?

Coins were also minted with holes on purpose. The most famous one of these are the Ancient Chinese coins. They were made with square holes because the hole made it easier to string when the hole was square. There are also coins with holes and loops through the holes.

What countries have square holes in their coins?

Holed coins are less rare than one would think, and coins from the countries of China, Korea, Japan, and Vietnam were mostly made with holes in them until the late 1800s. Most of these coins had square holes, and this was due to the production process.