1. Blue glazed porcelain in Ming Dynasty is much less than blue and white porcelain, and it is also much more precious. The developer of blue and white is cobalt, which is relatively rare, and high-quality cobalt is very rare.

2. A blue-glazed porcelain consumes much more cobalt than a blue-and-white porcelain, which is an important reason why blue-glazed porcelain is much less and more precious than blue-and-white porcelain.