kuri-iro 皀色

Also kuri 皀. A shade of black or dark grey. A dye of this color is made from tannin found in the oak tree Quercus Acutissima, and used with an iron or lye mordant. Kuri-iro dyed clothes are thought to have been worn by low ranks in society, and are mentioned as early as the 8th century in the Nihon shoki 日本書紀.