It's approximately 17cm in diameter. I'm not familiar with pottery, so I don't know the details. There's a small crack. The blue glass inside and around it is lovely and looks great just by displaying it. ↓ Here's an AI description: A black ceramic bowl featuring blue patterns and dripping glaze. - Color: Black and blue gradation - Design: Blue patterns on the inside - Features: Dripping glaze design - Material: Ceramic Thank you for looking.