Yellow tiles were reserved for the imperial palace, green for princes and other members of the imperial family, blue for the nobility, and ordinary clay for the populace.
杜甫「碧瓦朱甍照城廓」的詩句，便是琉璃瓦的形容。那時琉璃瓦還以色分級：黃色為帝王宮殿專用，太子與諸侯宮室用綠瓦，公侯之外的官僅能用青瓦，平民則仍用土瓦。