Fig. 6

Polarized microscope photos of blue pigments used in different dynasties in Cave 256. a, b blue pigment used in the Five Dynasties; c, d dark blue pigment used in the Song Dynasty; e, f blue pigment used in the statue in the Qing Dynasty

Polarized microscope photos of blue pigments used in different dynasties in Cave 256. a, b blue pigment used in the Five Dynasties; c, d dark blue pigment used in the Song Dynasty; e, f blue pigment used in the statue in the Qing Dynasty