Mauryan polish describes one of the frequent characteristics of architecture and sculptures of the Maurya Empire in India (325 to 185 BCE), which gives a very smooth and shiny surface to the stone material, generally of sandstone or granite. Mauryan polish is found especially in the Ashoka Pillars as well as in some constructions like the Barabar Caves. The technique did not end with the empire, but continued to be "used on occasion up to the first or second century A.D.", although the presence of the polish sometimes complicates dating, as with the Didarganj Yakshi. According to the archaeologist John Marshall: the "extraordinary precision and accuracy which characterizes all Mauryan works, and which has never, we venture to say, been surpassed even by the finest workmanship on Athenian buildings". Barabar Caves The Barabar caves are the first known and dated example of Mauryan polish, since they were dedicated by Ashoka in several inscriptions, in the year 12 and the year 19 of his reign. The caves were carved out of granite, an extremely hard rock, then finished with a very fine polishing of the inner surface, giving a mirror effect of a great flatness, as well as an echo effect. This large-scale polish directly evokes polishing on smaller surfaces of the Maurya statuary, particularly visible on the pillars and capitals of the Pillars of Ashoka. This know-how seems to have disappeared again after the Maurya period, none of the subsequent caves such as the Ajanta Caves having this characteristic of polished surfaces At Barabar Caves, some caves where dedicated through inscription by Ashoka (the caves of the Barabar group), as well as by his grandson and successor Dasaratha Maurya (the caves of the Nagarjuni group). Both group of caves have perfectly polished walls, which suggest that polishing techniques were not exclusive to Ashoka, and continued as least for some time after his reign. Later Caves After the Barabar Caves, the polishing of cave walls was abandoned, never to be revived, despite the huge efforts at building Buddhist and Jain caves until the 6th century CE.