What stone is the best in Yishui inkstone?

Jade jade Dai Yushi blue-gray inkstone is hard, solid and smooth, produced in Xiyu Mountain in the southeast of yi county, with rich colors, different shades and obvious layering, and rich stone products such as natural waterlines, so Yishui inkstone is the best. Yishui inkstone is one of the famous Gu Yan in China. Often regarded as the originator of inkstone, it is as famous as Guangdong's Duanyan. Known as "the south end is easy to the north".