This is why in ancient times ciqing paper was extremely rare and valuable. In the Ming dynasty, one sheet could be exchanged for ten catties of white flour. When the Qing emperor Qianlong (reigned 1736-1795) had his prime minister Liu Luoguo (familiar to Taiwanese TV audiences from a mainland drama series) transcribe Buddhist scriptures as a birthday present for his empress, Liu wrote them in gold paste on ciqing paper.
也因此古代的磁青紙極其珍貴，明朝時一張可換白麵十斤；乾隆皇帝讓宰相劉羅鍋寫給太后作為生日禮物的佛經，也是以泥金寫在磁青紙上的。