Wu Collection, Lower Volume Radical: Stone (shí) Li Kangxi Strokes: 20 Page 838, Entry 23 According to the Tang Rhyme (Tangyun), Collection Rhyme (Jiyun), and Collection of Rhymes (Yunhui), the pronunciation is li (falling tone). In the Classic of History (Shujing), specifically in the Charge to the Marquis of Fei (Feishi) chapter, it states: Sharpen your blades. The commentary explains this as a whetstone. The rectifications state: Li refers to coarse whetstones, therefore di is finer than li. The Jade Chapters (Yupian) states: The mountains of Yanzishan produce whetstones, which can be used to sharpen blades. The Explanation of Script (Shuowen) notes that in the classics, this character is often used interchangeably with the form pronounced li (falling tone).