Qiu Jiao means that the sea ivory is dyed emerald green. Its cross-section is brain-shaped, denser than ivory, and has a certain feel and texture. This process of dyeing sea ivory green is unique to the Qing Dynasty office, with products such as cigarette butts, leeches, seals, small gourd covers, blindfolds, gas eyes and other small objects. This craft spread to the folk in the Qing Dynasty, but only a very small number of craftsmen knew it, and now it has almost been lost.