Diagnostic Study of a Flower-Shaped Bowl with Icy Tianqing Glaze (Guan yao, Late Southern Song – Early Yuan)

Prof. Nona Dronova

Doctor of Technical Sciences, Professor of Traditional Arts, St. Petersburg
📖 Published in: Nona Dronova, "What You Must Know About Ancient Chinese Porcelain", Moscow, 2016, p. 13. ISBN: 978-5-9908782-6-6

📄 Abstract

This study presents a comprehensive diagnostic analysis of a flower-shaped bowl attributed to the Guan yao (official kiln) tradition of the late Southern Song – early Yuan period. The bowl features a thick, icy Tianqing-type glaze with natural crackle, an iron-burnt unglazed foot, and a violet halo at the rim — all strongly consistent with official kiln standards. Microscopic examination reveals a fine crystalline glaze texture, a natural crack network without artificial staining, and precise glaze-body transitions. Additionally, instrumental color analysis confirms the grey-green tone as belonging to the “stony” Tianqing glaze subtype, further supporting attribution. The object is published in the author’s monograph and is proposed as a diagnostic reference for authentic Guan yao ware.

🏺 Object Description

• Catalogue No.: GE-FL-11-CB-01

• Title: Flower-shaped bowl with icy Tianqing glaze

• Date: Late Southern Song – early Yuan (12th–13th c.)

• Attribution: Guan yao, Laohudong kiln system

• Material: High-fired porcelain with Tianqing-type glaze

• Dimensions: 11 cm diameter × 7 cm height

• Shape: Chrysanthemum form with petal-like lobes

• Foot: Unglazed, iron-burnt with visible shrinkage line and violet optical zone

• Glaze: Grey-green, glassy, with fine icy crackle and oily translucency

🔬 Diagnostic Features Confirming Authenticity

1. Natural Ice Crackle Glaze

The glaze surface exhibits dense, naturally formed ice crackle (tianlan wen 天蓝纹) without pigment infill — typical of official Song wares.

Figure 1. Underside of the bowl showing unglazed foot, icy Tianqing glaze, and violet halo.

2. Microstructure of the Glaze

Under magnification, the glaze shows a uniform microcrystalline matrix and soft internal reflection, suggesting a high degree of glaze purification.

Figures 2 & 6. Close-up of crystalline surface with subtle reflectivity and light diffusion.

3. Crack Anatomy and Iron-Rich Edges

Natural cracks are deep, sharp, and exhibit localized iron-rich edge deposits under magnification.

Figure 3. Clean crack structure with reflective surface and no artificial enhancement.

4. Glaze–Body Transition

The glaze terminates cleanly with a well-defined shrinkage line above the iron-burnt foot zone, confirming high-temperature reduction firing.

Figure 4. Interface between glazed wall and burnt foot.

5. Violet Optical Halo

A violet to lavender optical hue is observed at the glaze cutoff — a rare and authentic optical phenomenon seen in high-end Guan yao specimens.

Figure 5. Violet tinge at iron-burnt rim due to reduction atmosphere.

🎨 Instrumental Color Analysis

The glaze color was sampled using digital imaging under calibrated lighting conditions:

• RGB: (151, 160, 148)

• HEX: #97a094

This color matches a light, muted grey-green tone, characteristic of the “stony” subtype of Tianqing glaze (天青釉). It shows:

• High lightness

• Low chroma (desaturated tone)

• Cool neutral undertone

Such color properties are consistent with late Southern Song official kilns, especially for refined ritual bowls and incense vessels produced in Laohudong workshops.

📘 Comparative References

✅ Conclusion

The flower-shaped bowl GE-FL-11-CB-01 exhibits a full set of diagnostic markers consistent with authentic Guan yao wares of the late Southern Song to early Yuan period. Its glaze tone, violet halo, crackle morphology, and microstructure match known standards from major collections. The piece is recommended as a diagnostic benchmark for researchers and institutions working with Song official ceramics.

📎 Figures and Captions

📚 Reference Publication

This bowl is published and fully documented in:

Dronova, Nona. "What You Must Know About Ancient Chinese Porcelain", Moscow, 2016, p. 13.
ISBN: 978-5-9908782-6-6

🔑 Keywords

Guan yao, Tianqing glaze, Song dynasty ceramics, Ge ware, official kilns, crackle glaze, reduction firing, violet halo, ceramic diagnostics, flower-shaped bowl, Southern Song porcelain, Chinese art history