The Precious Collection of the Stone Moat exhibition at the Palace Museum last year helps improve knowledge of classical Chinese painting and Emperor Qianlong's collecting philosophy.[Photo provided to China Daily]

Many items cataloged in the inventory were taken out of the Forbidden City (Palace Museum), and some even transported abroad, following the decline of the Qing Dynasty, social chaos, wars and other reasons.

Now, only about 1,200 pieces cataloged in the inventory remain at the Palace Museum.

Paintings and calligraphy scrolls listed in the catalog's three volumes are still sought after by potential buyers since the mainland art market started to boom in the 1990s.

In auction catalogs, a note saying "formally cataloged in the Precious Collection of the Stone Moat" is a strong indication of the work's authenticity and significance.

Another bible for collectors is the Catalog of Classical Chinese Paintings and Calligraphy compiled by a team of prominent connoisseurs, such as Xie Zhiliu, Qi Gong and Xu Bangda, in the early 1980s.

They examined hundreds of collections in both private hands and public institutions, and the catalog records their judgments, including their different opinions on the genuineness of particular works.

These catalogs are typically used when collectors need to identify a featured artist's other works.