Determining genuine Ming Dynasty, Chenghua (1465-87) blue and white from
later Qing Dynasty, Kangxi (1662-1722) copies is one of the greatest challenges
in porcelain connoisseurship.
During the 200 year span between the two reigns, the methods and artistry
of the potter improved. By the end of the reign of Kangxi, the artists had
become expert at both subtle and dramatic graduation in the application of
cobalt. Very little streaking or wash overlapping within the outlined areas
Imported cobalt from the Xuande expeditions of 1426, 30, 33, and 34 had run
out by the reign of Chenghua and native Chinese cobalt had to be used. The
next (and last) shipment of Mohammedan Blue to arrive from Sumatra was in
1486, too late to have any affect on porcelains from this reign.
Native Chinese cobalt was also used during the reign of Kangxi, so this also
adds to the difficulty of determining authenticity.
Examination of Item M1 reveals the property of the cobalt to be native Chinese
versus the imported variety. Chinese cobalt has manganese, a hard,
brittle, grayish metallic element with an oxidizing property. The firing
process causes the blue to be tinted slightly gray (fig 2). The imported
variety, known as Persian or Mohammedan blue, is a deeper and
brighter blue without the presence of manganese (fig 1). Though
the import variety was now available, Chinese cobalt remained in use through
the reign of Jiajing (1522-66) (fig 3). The use of native Chinese
cobalt during the Qing dynasty reign of Kangxi is shown in figure 4.
The slight streaking in the washtones and the overlapping with the
diluted wash in the outlined areas are characteristic of genuine
Chenghua, though Imperial grade is near perfect. The smooth creamy
glaze with microscopic bubbles present in the cobalt areas are also
characteristic to Chenghua, as is the smooth biscuit and the thin delicate
potting. The orange iron oxide discoloration visible where the
biscuit is exposed is further proof, as the copies produced during Kangxi
were of near perfection in both decoration and firing.
The style, decoration, and physical properties of item M1 conclude it to
be authentic Ming Dynasty, Chenghua (1465-87).