The fascination with Jun ware lies in its remarkable glaze, with its lustrous and opalescent qualities, as evident in the present lot. This opalescence is due to the effect of light on certain features within the glaze: the mass of tiny gas bubbles trapped in the glaze, the formation of minute crystals which reflect light back through the glaze, and an emulsion formed by two liquids within the glaze. Early examples of junyao have an even pale bluish glaze. Later, the potters began to add splashes of copper oxide to the unfired glaze, which resulted in colourful pieces comprised of bright purple areas contrasting with the soft blue tone of the glaze. On 'narcissus' bulb bowls, the most desirable arrangement was to have the interior glazed blue and the exterior purple.
Research has suggested that the numbers incised on the bases of junyao vessels, clearly relate to the size of the vessel and may also indicate which rooms they were kept in at the Imperial Palace. As a rule, the larger the numeral on these 'numbered' Jun wares, the smaller the size of the vessel. These bulb bowls were often called 'drum-nail' bowls, as the bosses symmetrically spaced in relief around the rim recalled the pegs used to tighten the skin stretched on top of a drum to change pitch.
Compare with published bulb bowls, of similar size and the same purple glaze covering the exterior wall and bluish interior, such as in The National Palace Museum, Taipei, included in the Illustrated Catalogue of Sung Dynasty Porcelain, pl. 66, and exhibited in A Panorama of Ceramics in the Collection of the National Palace Museum: Chun Ware, 1999, Catalogue, no. 32; and another bowl inscribed with the same numeral 'five', illustrated ibid., Catalogue, no. 33.
A similar bowl inscribed with the number 'four' from The Robert Chang collection was sold at Christie's Hong Kong, 28 November 2006, lot 1304.
Fragments of several 'drum-nail basins' of this form from the Jun ware kiln sites at Baguadong, Yuxian, Henan, with different numerals incised on the base, were included in the O. C. S. Exhibition of Kiln Sites of Ancient China, London, 1980, Catalogue nos. 394-397.