Xu Collection, Upper Volume Radical: Metal (jīn) Bo Kangxi strokes: 13 Page 1301, Entry 01 According to the Sound Rhymes (Jiyun), it is pronounced bo. It refers to thin gold leaf. According to the Correct Character Encyclopedia (Zhengzitong), gold leaf is thin gold. It is made by hammering gold flakes between sheets of medicinal paper; the gold becomes thin, and the paper remains undamaged. The paper is initially brownish in color, but over time, the color resembles black gold. Originally, the character for thin was borrowed for this, but through common usage, the metal radical was added to create this character.