Shan Tao, courtesy name Juyuan, was one of the famous "Seven Sages of the Bamboo Grove" during the Wei and Jin dynasties. He was pure in character and exceptionally insightful. Although he was related to the ruling Sima family, he never flattered them, so he only became a minor registrar in the commandery at age 40.
Later, the Sima clan usurped Wei and established the Jin dynasty. Shan Tao was appointed Minister of Personnel. Ji Kang, one of the "Seven Sages of the Bamboo Grove," broke off relations with him, writing a "Letter to Shan Juyuan on Breaking Off Relations." Ji Kang was later executed by Sima Zhao.
Two years later, Shan Tao recommended Xi Kang's son, Xi Shao, to Emperor Wu of Jin, Sima Yan, praising him as both virtuous and talented and fit for office. Xi Shao was appointed as a secretary in the imperial library.
Soon after, a powerful minister named Jia Chong recommended his trusted ally Lu Liang to Emperor Wu of Jin, praising him as loyal, upright, and impartial, and requested that he be appointed to the Ministry of Personnel. The emperor agreed. However, Shan Tao, knowing Lu Liang to be a petty schemer, strongly opposed the appointment. When the emperor ignored his objections, Shan Tao resigned and returned to his hometown. Not long after, Lu Liang was investigated and dismissed for corruption. The emperor then recalled Shan Tao, placing even greater trust in him than before.
Shan Tao served in the Ministry of Personnel for over 20 years, recommending many officials to the court. Because he had a keen eye for talent, the evaluations in his memorials closely matched their later performance. People at the time called these memorials "Shan Tao's Recommendations."
Because Shan Tao enjoyed great prestige among the scholar-official class of his time, Wang Rong, one of the "Seven Sages of the Bamboo Grove," once praised him, saying, "Shan Tao is like unpolished jade and unrefined gold. People admire the brilliant exterior of jade and gold, yet they fail to recognize the noble inner quality of unrefined gold and unpolished jade."
It should be said that Wang Rong's assessment of Shan Tao was quite accurate.
Later, the idiom "Unrefined Gold and Uncut Jade" came to describe a person's pure and simple character, or naturally unpolished yet exquisite objects.
Source: *A New Account of the Tales of the World*, Chapter "Appreciation and Praise"
Meaning of the Idiom: Later, the Chinese idiom "浑金璞玉" came to describe a person's pure and simple character, or naturally unpolished yet exquisite objects.