1 Cash - Daoguang Tongbao, Boo-kiyan

The Boo-kiyan mint — romanized from the Manchu name for Beijing — was one of the two capital mints operating under direct Board of Revenue supervision, making its output subject to stricter weight and alloy controls than provincial issues. During Daoguang's reign, those standards were increasingly difficult to maintain. Chronic copper shortages and treasury pressures led to repeated official reductions in the cash coin alloy ratios, and Boo-kiyan pieces from the later years of this reign often reflect that degradation in both color and density.