The round rim and square hole unite heaven and earth, while the set of three represents the harmony of heaven, earth, and humanity. The red thread is said to awaken the coins' metal energy, drawing wealth and keeping abundance in circulation.
Old Chinese cash coins carry the ancient idea that "heaven is round, earth is square" — a round body pierced by a square hole. Feng shui prizes coins minted in prosperous reigns, especially the Qing emperors Kangxi and Qianlong, and the tradition grew of tying three together with red thread as a charm for wealth.
The round rim and square hole unite heaven and earth, while the set of three represents the harmony of heaven, earth, and humanity. The red thread is said to awaken the coins' metal energy, drawing wealth and keeping abundance in circulation.
They are kept in a wallet or cash box, or hung inside the front door and by the till, always bound with red thread. A set of coins is also a favorite gift for a business opening.