18th century iron-red and underglaze blue moon flask, estimated at €300,000-500,000 at Nagel.

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Although this auspicious pattern and colour combination is found on dishes from the Yongzheng and Qianlong periods, the 14in (35cm) high dragon-handled flask in the sale, which has an estimate of €300,000-500,000, appears to be other half of the only existing pair.

It is one of 36 works of art in the sale from the collection of Franz Karl Ivo Streich (1857-1920), a German diplomat who was vice consul in the coastal town of Swatow (Shantou) for 17 years.

The corresponding, well-documented piece belongs to the Songzhutang Collection of Imperial Chinese Ceramics in Hong Kong.