Memorial Porcelain Vases in Commemoration of the Kangxi Emperor: Rare Okra-Green and "Black Gold" Glazes with Famille Verte and Underglaze Cobalt Motifs

Author: Professor Nona Dronova, DSc — ORCID: https://orcid.org/0009-0007-4867-9074Planned DOI: 10.5281/zenodo.16927842License: Text CC BY 4.0; Images & Micrographs CC BY‑SA 4.0Series: Continuation of Zenodo publications on rare Qing glazes (see DOI: 10.5281/zenodo.16894544; 10.5281/zenodo.16882538; 10.5281/zenodo.16889063). Abstract This study examines two rare memorial porcelain vases dedicated to the artistic achievements of the Kangxi Emperor (1662–1722) and bearing Yongzheng reign marks (1723–1735). The first employs an unusual okra‑green ground with famille verte panels, the second a highly lustrous black glaze, often referred to as “black gold”, with underglaze cobalt reserves. High‑magnification microscopy revealed lead–silica phase separation, micro‑bubble populations, thin‑film iridescence, and craquelure networks diagnostic for early‑18th‑century Qing glazes. The okra‑green ground is constructed as a stratified system: a copper‑bearing enamel layer overlaid by a transparent lead‑silicate glaze. The mirror‑black glaze consists of a pigment‑rich Fe–Mn–Co matrix with dense subsurface fissuring and a metallic sheen. Both colorways are confirmed as rare in museum corpora and are linked to imperial Jingdezhen production in the Kangxi–Yongzheng transition. Comparative references to technical literature and museum catalogues confirm their rarity and technological sophistication. Keywords: Kangxi Emperor; Yongzheng; Qing dynasty porcelain; memorial wares; okra‑green glaze; mirror‑black glaze (wujin you); famille verte; underglaze cobalt; phase separation; craquelure; imperial kilns Jingdezhen. 1. Introduction Memorial porcelain vases in honor of Kangxi’s cultural and artistic legacy often combined two hallmark traditions of Qing porcelain: underglaze cobalt (qinghua) and enamel decoration (famille verte). The two examined pieces embody this synthesis while deploying two rarely attested glaze grounds: (i) an okra‑green enamel ground and (ii) a lustrous mirror‑black glaze described as “black gold”. These colorways are associated with small‑batch, high‑specification productions at the imperial kilns of Jingdezhen, reflecting Yongzheng’s continued commemoration of Kangxi’s achievements. 2. Materials and Methods Specimens. Two baluster vases with flared rims. One vase has an okra‑green enamel ground with famille verte reserves; the other a mirror‑black glaze with underglaze cobalt cartouches. Both bear a six‑character Yongzheng mark in underglaze blue within double circles. Microscopy. Optical microscopy at magnifications up to 400× was applied to glaze fields, pigment islands, boundary zones, and the reign mark. Illumination under raking light was used to identify iridescence and micro‑craquelure. No destructive sampling was conducted. Comparative literature. Results were cross‑checked with published technical studies on lead‑silicate enamels (Kerr & Wood 2004; Wu 2019; Colomban 2021) and manganese–iron mirror‑black glazes (Medley 1977; Li & Zhang 2016; Guo 2020). 3. Results: Okra‑Green Ground Microstructure. The green enamel shows a dispersed population of micro‑bubbles (1–10 μm) and opaque crystalline inclusions acting as opacifiers. Boundary micrographs confirm a stratified construction: (G1) a copper‑bearing colored enamel, (G2) a transparent lead‑silicate overglaze providing depth and gloss. Local bands of iridescence correspond to thin‑film interference typical of lead‑rich matrices. Comparative reference. A bowl in the Palace Museum, Beijing (catalogued as “yellowish‑green/okra glaze”, Yongzheng reign), shows the same two‑layer construction: an opaque enamel applied over a transparent glaze and re‑fired. The color derives from copper chromophores in a lead–antimonate matrix (British Museum, PDF B.526; Palace Museum Catalogue 2008). These features match the stratigraphy observed in the present vase. 4. Results: Mirror‑Black “Black Gold” Glaze Microstructure. The black glaze presents a dense, vitreous surface with mirror‑like reflectivity and a tight network of craze lines (50–200 μm spacing). Subsurface fissures and crystalline speckling are visible in grazing light. Boundary analysis reveals a pigment‑rich layer (Fe–Mn with minor Co) over a clear glaze base. Localized metallic sheen supports the description as “black gold”. Comparative reference. Mirror‑black wares (wujin you) are documented as Yongzheng‑era special productions, sometimes gilded (Medley 1977; J.J. Lally & Co. 2014; Metropolitan Museum of Art Collections). Their rarity is underlined by the limited number of extant examples in major museums. 5. Reign Mark Microscopy The six‑character Yongzheng mark in underglaze blue shows feathering edges, micro‑pinholes at stroke overlaps, and granulated cobalt particles embedded beneath the glaze, consistent with kiln‑fired underglaze application. 6. Discussion: Rarity and Context Okra‑green enamel. Museum and catalogue records confirm the rarity of this glaze. The Palace Museum (Beijing) and the British Museum describe such grounds as “okra” or “yellowish‑green”, produced via copper‑bearing enamels applied over a transparent glaze and re‑fired (Palace Museum 2008; British Museum PDF B.526). This confirms the high technical demands of the glaze and its status as a court innovation of the Yongzheng era. Mirror‑black glaze. Mirror‑black (wujin) wares are likewise rare. Research identifies them as manganese–iron–cobalt based systems developed at Jingdezhen. Their dense micro‑craquelure, metallic sheen, and reflective quality are distinctive (Medley 1977; Kerr & Wood 2004). They are represented by a small number of museum holdings (Metropolitan Museum of Art; Worcester Art Museum). Together, both glazes illustrate the experimentation and refinement of Yongzheng imperial kilns in commemorating Kangxi’s artistic legacy through rare and technically complex chromatic effects. 7. Conclusions The okra‑green enamel ground is a stratified system with a copper‑bearing layer beneath a transparent lead‑silicate glaze, showing phase separation, bubbles, and thin‑film iridescence. The mirror‑black glaze is a Fe–Mn–Co pigment matrix with tight micro‑craquelure and metallic luster. Both glazes are rare within museum corpora and confirm small‑batch imperial productions of the Yongzheng period. The combination of famille verte enamels and underglaze cobalt reflects a commemorative synthesis of Kangxi aesthetics under Yongzheng. Figures Fig. 1a–b. General views of the two vases (okra‑green ground; mirror‑black ground). Fig. 2. Yongzheng six‑character reign mark (underglaze blue, double circle). Fig. 3. Okra‑green glaze micrograph showing bubble field and opacifiers. Fig. 4. Okra‑green glaze stratigraphy (colored enamel + clear lead glaze). Fig. 5. Underglaze cobalt reserve, pigment granulation. Fig. 6. Mirror‑black glaze with micro‑craquelure network. Fig. 7. Mirror‑black/cobalt boundary, subsurface fissuring. Fig. 8. Palace Museum bowl with okra glaze (comparative example). Acknowledgements The author thanks the custodians of the memorial vase pair for access and permission to publish macro and micro imagery under open licenses. Data Availability All original photographs and micrographs will be deposited to Zenodo together with this article (open access). References Kerr, R. & Wood, N. (2004). Science and Civilisation in China. Vol. 5, Part 12: Ceramic Technology. Cambridge University Press. Medley, M. (1977). The Chinese Potter: A Practical History of Chinese Ceramics. Oxford University Press. 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