LONDON.- The precisely constructed elements of a white jade hinge-fitting made for the Qianlong Emperor (reign 1736-1795), might have served to remind him of his duty to be scrupulous and precise in his own rule. This beautiful object, estimated at £200,000 to £300,000, is one of the top items in Bonhams sale of Fine Chinese Art on May 15th in London.

Scholars still do not know the precise meaning of this culturally intriguing object. Bearing a Qianlong six-character fang gu mark and of the period the pure white stone is of exceptional clarity, unusually carved with two rectangular hollowed tubes, each of the wider sides carved in mirror image to suggest an archaistic mask.

The hinge-fitting embodies much of the artistic and historical pre-occupations of the Qianlong period. Carved from exceptionally fine and lustrous white stone, with even the minor flaws most cleverly incorporated into the scrollwork, the thinly hollowed supremely challenging yet technically flawless piece is representative of the highest skill of the 18th century craftsman. Furthermore it falls into a group of jade pieces carved with the Qianlong fanggu mark, specifically carved with archaistic designs inspired by archaic bronzes to reflect the concerns of the Qianlong Emperor with drawing moral strength and righteousness from the examples of the ancients.

A few examples of jade pieces designed to the same specifications as the present lot are preserved in the most prestigious museum collections, including a white jade piece in the Palace Museum, Beijing.

The design has been and remains, to scholars, collectors and curators, a most intriguing puzzle. The form has ancient origins, and its ancient bronze prototype can be found in the Catalogue of Xiqing Antiquities, which was an illustrated catalogue of ancient bronzes in the Imperial Collection, completed in 1751. However even the cataloguers could not describe the bronze prototype other than as a 'Han Dynasty ornament' and to state that the two tubes are movable.

It is interesting to compare the present lot and those in museum collections with another white jade hinged piece which is further unusual in being inscribed with an Imperial poem. The poem appears to refer to the jade piece as a 'ruler' to be used to 'compare lengths' with 'precisely fitting workmanship'. This pre-occupation with the idea of measuring is also connected to the idea of the benevolent ruler who is guided well.