Two Chinese characters Ban Liang ("Half an ounce"), no rims or other marks / Blank, no rims. 31mm, 10.00 grams. Gratzer/Fishman "The Early Round Coins of China" #12.3; Hartill #7.7. 

The earliest Qin dynasty coins cast in 221-220/219 BC were heavy (~8-19 grams) and were of extremely variable weight and size. However, at least some such variable heavy coins were probably cast in the earlier period, before 221 BC, and some of the very heavy large Ban Liangs could have been cast during the Imperial period (221-210 BC). 

Qin Shi Huangdi (259 BC - 210 BC) was king of the Chinese State of Qin from 246 BC to 221 BC during the Warring States Period. He became the first emperor of a unified China in 221 BC. He ruled until his death in 210 BC at the age of 50. Qin Shi Huang is a pivotal figure in Chinese history. After unifying China, he and his chief advisor Li Si passed a series of major economic and political reforms. He undertook gigantic projects, including the first version of the Great Wall of China, the now famous city-sized mausoleum guarded by a life-sized Terracotta Army, and a massive national road system, all at the expense of numerous lives.

This coin is unconditionally guaranteed to be authentic.