A rare variety of ancient celadon, whose production technique was lost more than a millennium ago, has captivated the public's imagination.

They were placed inside a lacquered wooden box, wrapped in silk and hidden in an underground treasure chamber that had been sealed for more than a thousand years-until an accidental discovery 33 years ago.

They were 13 pieces of the legendary mise celadon, discovered in 1987 in Famen Temple's underground palace in Baoji, Shaanxi province, when work was being done on the holy site.

The Chinese characters for "mise ware "were inscribed on a stone tablet in the palace. It listed items that Tang Dynasty (618-907) emperors had presented to Buddha.

Mise (literally, "secret-color") celadon was created using a technique lost more than a millennium ago. It was primarily produced for the imperial court.

Prior to the discovery, people could only imagine its beauty based on limited clues from ancient texts, such as a poem that compares mise celadon to "a piece of the moon dyed with spring water".

In 2016, mise celadon was unearthed at the Housi'ao kiln, part of the Yue Kiln Sites at Shanglin Lake in Cixi, Zhejiang province. Studies have shown that this was the much-admired porcelain's production site.

Mise ware represents the finest of Yue celadon, which features a grayish shade of green and tactility that make it jade-like.

"One thing that sets mise celadon apart is its crystalline texture," says Du Liuqi, a staff member at the Shanglin Lake Yue Kiln Museum in Cixi.

"A mise vessel is so smooth and translucent that it looks like there is water in it when there isn't. To ensure the quality of mise, ceramists made its sagger using the same fine materials for making the ware itself to minimize contamination during firing, as opposed to the containers made of average-quality clay for regular celadon.