金壶墨汁

Explanation: Refers to the extremely valuable rare painting supplies. 　　Source: Jin Wangjia "King Ling Shi Yi Ji Zhou" floating mention of the country offer two-pass a good book, at first glance little old at first glance, stealth is silent, heard this is invisible, a four-inch pot of gold between the elbow, on Wulong The inspection, sealing the blue mud, ink pot, such as sun in paint, and stone throwing in, all bucket of words into Zhuanli Division. "