According to Tang Rhyme (Tangyun), pronounced dang (level tone), gu (rising tone). According to Collected Rhymes (Jiyun), pronounced dong (rising tone), wu (rising tone); the pronunciation is the same as du. Jade Compendium (Yupian) defines it as a beautiful stone. Also, according to Tang Rhyme (Tangyun), pronounced hou (rising tone), wu (rising tone). According to Collected Rhymes (Jiyun), pronounced hou (rising tone), wu (rising tone); the pronunciation is the same as hu. The meaning is the same.