pearl, bead

珠 is composed of the radical 玉 (jade) and 朱 (vermilion). 朱 depicts a tree with a mark painted on its trunk. In order to make the mark easy to see, it was usually a large red dot. Therefore, 珠 conveys the idea of a round particle whose luster is like that of fine jade. Originally, 珠 referred to the round particle produced inside a clam shell, and later it came to broadly refer to all round particles.