Can the idiom "Yi Zi Qian Jin" mean that calligraphy works are very precious?

Yes

One word thousand gold [yī zì qiān jīn]

Explanation: One word for increase or loss, a thousand gold reward. The words of praise are exquisite and cannot be changed.

From: "Historical Records·Biography of Lu Buwei": "Build it at the gate of Xianyang City, hang a thousand gold coins on it, and invite the princes, tourists and guests who can add or lose a word to give a thousand gold coins."

Example: The text is gentle and beautiful, the meaning is sad but distant, thrilling, almost ~

◎Liang Zhongrong's "Poetry" Volume 1

Source

Southern and Northern Dynasties·Zhong Rong's "Poetry·Ancient Poetry": "The writing is gentle and beautiful; the meaning is sad and distant; thrilling; almost every word is worth a thousand dollars."

Example sentences

Mr. Lu Xun's essays, The meaning is very profound, it is really ~.