[2] The earliest excavated inkstone is dated from the 3rd century BC, and was discovered in a tomb located in modern Yunmeng, Hubei.

[4][5] The Qianlong Emperor had his own imperial collection of inkstones catalogued into a twenty-four chapter compendium entitled Xiqing yanpu (Hsi-ch'ing yen-p'u).

Qing dynasty emperors often had their inkstones made of Songhua stones, but this choice was not popular outside of the imperial workshop.

However, by the late Qing dynasty, the inkstone market had turned to favoring highly intricate and novel designs.

[4][8] Two types of rock are mainly used to make inkstones:[1] The ink stone consists of a flat part called the “hill” (qiū [丘] or gāng [冈]; oka [丘] or [岡] in Japanese), and a hollow part “the sea”, hǎi, 海 (umi in Japanese) intended to collect the ink created.

But quarrying these stones was dangerous and strenuous, as they were usually found in caves particularly hard hit by violent floods.

Even today, many mines are still in operation, and the oldest stones over a hundred years old, also known as guyàn / ko-ken (古硯), are much more sought-after than the newer ones known as xinyàn / shin-ken (新硯).

[13] More water is gradually added during the grinding process to increase the amount of ink produced, the excess flowing down into the reservoir of the inkstone where it will not evaporate as quickly as on the flat grinding surface, until enough ink has been produced for the purpose in question.

The inkstone, together with the ink brush, inkstick and Xuan paper, are the four writing implements traditionally known as the Four Treasures of the Study.