with four character reign mark of the Qianlong emperor, cylindrical archaistic oval bamboo form vase/brush pot, with auspicious symbolism throughout the design, sides flanked with double clouds and chilongs, one leafy bamboo stalk, Greek key fret at rim, gilt inscribed Imperial poem, celadon coloring with minor black inclusions throughout, 4-3/8 x 2-7/8 x 1-3/4 in.

Note: This tests as nephrite on the Presidium Gem Tester II.

The rare calligraphy of the imperial reign mark on the base is possibly the work of jade craftsman Zhu Cai. For a jade object with a similar signature, please view Christie's Auction #16759, 2018, Lot 2930. https://www.christies.com/lot/an-important-and-extremely-rare-imperial-yellow-6146029/?intObjectID=6146029&lid=1. 

Zhu Cai, the jade craftsman, was a famous engraver of calligraphy in the court workshops during the early Qianlong reign. He was selected by the Suzhou Central Bureau of Textiles to serve at the palace jade workshop inside the Zaobanchu. His name is frequently found in the Zaobanchu records between the Qianlong eighth to twenty-second year, in which he was often ordered to inscribe reign marks or Imperial poems, and to execute intricate diaper ground designs on jade pieces, as well as to carve Imperial seals.

A gilt inscription of a Tang Dynasty poem by Du Fu titled "嚴鄭公宅同詠竹" (Yan Zheng’s residence and Yongzhu). The poem loosely translated into English reads: 

The green bamboo is half-sheathed, and the new shoots have just emerged from the wall.
The color of the bamboo is infiltrating the bookcase in the evening, and the shade is over the wine bottle.
The rain washes it clean, and the wind blows it with a delicate fragrance.
If you don't cut it, you will see it grow long and brush against the clouds.

According to the seller of this object, it was acquired from a private collection from Boston, Massachusetts which included objects acquired in China with a Boxer Rebellion history, the previous history is unknown.  The seller was informed this piece could possibly be Khotan jade.