Note 36 — Chapter XI · Tree-, Herb-, and Stone-lore
Reading edition
Stones were likewise graded. Precious stones had more ling than ordinary stones. Precious stones are sometimes referred to as pi-si. One Chinese writer says that “the best pi-si are deep-red in colour; that those in which purple, yellow, and green are combined, and the white ones take the second place; while those half white and half black are of the third grade”.36