A craftsman processes a Sizhou inkstone carving in a studio in Cengong county, Southwest China's Guizhou province, Nov 30, 2017. Sizhou inkstone, mostly produced in Cengong county, has a history of thousands of years. For serious calligraphers and painters, the quality of the inkstone is just as important as the quality of the ink that is ground inside of it, as the inkstone can affect the ink's texture. Paper, ink, brushes and inkstones -- otherwise known as the "four treasures of study" -- are the primary tools used in Chinese calligraphy and painting. [Photo/Xinhua]