Among the four treasures of the study, there are paper, ink, pen and inkstone. Among them, the most famous ink is Hui ink, right? In the Qing Dynasty, Hui ink production was divided into four major master systems, namely Cao Sugong, Wang Jie'an, Wang Jinsheng and Hu Kaiwen, among whom Wang Jinsheng and Hu Kaiwen were both from Jixi County. They improved and innovated Huizhou ink on the original basis, and finally produced literary treasures that are like "gold cannot be exchanged", including Longxiangji ink, Tianchen ink, Xiantao core ink, Ziwei star ink, Yuxilian ink, Xihu ink Shijing ink and Earth ink are all peerless works, which give Huizhou ink the characteristics of "falling off the paper like paint, dark and moist color, lasting, no glue on paper and pen, rich fragrance, and smooth texture on the skin". Huizhou ink during this period can be divided into pine smoke, oil smoke, lacquer smoke and super lacquer ink according to different raw materials. The most valuable among them are high-grade oil fume ink such as super lacquer ink. This kind of ink exudes a purple jade luster and is used for calligraphy. The color is dark and moist; it is thick but not stagnant when used in painting, light but not gray, and has clear layers, so it has been highly praised by calligraphers and painters of all ages.