Antique Chinese Chinese Qing Dynasty “Ox blood” vases

From a 15 cm diameter foot ring the beautifully formed vase rises with a slightly waisted body to a high shoulder and finally to a flared trumpet lip.
The vase is of significant size, measuring approximately 47 cm tall and weighing 6.4 Kg, it stands upon a raised foot that exhibits a burnt orange ground inside the foot-ring, typical of the early Qing period. The foot-ring itself displays very old scuffing from the time of firing. Early oxblood glazes tended to run and stick to the kiln. Within the foot-ring and clearly visible is the incised 4 character stamp referring to Emperor Yongzhen (Yung-cheng).

The body has occasional kiln firing spots and exhibits surface crazing as would be commensurate. One vase has uneven foot rim, presumably where it become stuck to the floor during firing.
Photographs show this vase in both bright outside daylight and indoors subdued daylight.

No accompanying documentation.
Ex fine art auction house. No prior provenance.

This lot is for the pair of vases. Enquire if only one vase is required.

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About
The name ‘sang de boeuf’ refers to the colour of the vase, which is French for ‘ox blood’. The difficult manufacturing process of this shade, which is achieved through an oxidisation process of iron and copper, was first recorded in China between the 11th and 13th century. European earthenware producers were not able to replicate the lengthy firing process involved in the production of sang de boeuf until the 20th century, leaving China to monopolise on such wares for centuries.