San Zhu ("3 zhu") // Blank. 24mm, 2.1 grams. Hartill 8.1; Gratzer/Fishman #3.112.

The Chinese Three Zhu (三銖, San Zhu) coins were short-lived bronze cash coins cast during 119–118 BCE in the reign of Emperor Wu of Han, as part of a sweeping reform of the Han monetary system abolishing the centuries-old Ban Liang coinage. Introduced after earlier experiments with heavier and lighter denominations, the San Zhu coins were round with a square central hole and bore the simple inscription 三銖, indicating their nominal weight of three zhu (around 2 grams). The coins circulated only briefly before being replaced by the more successful and durable Five Zhu (五銖) coinage in 118 BC, which became the backbone of Chinese currency for centuries.