Is the grain of Ming Chenghua grape black?

No. We can't consider grapes as defective just because they turn black. Porcelain turns black due to the influence of external environment during storage or use. For example, long-term exposure to humid environment, exposure to harmful gases such as sulfide, or improper cleaning treatment may lead to blackening of grape grains. Need professional institutions or connoisseurs to carefully detect, identify and repair, and pay special attention to avoid further damage to the goods. Grape grains of Chenghua in Ming Dynasty are a precious thing, usually made of ceramics. During Chenghua period in the Ming Dynasty, porcelain-making techniques such as blue and white underglaze and red official glaze were used, which had high artistic value and collection value.