I'm not entirely sure, but it appears to be a handmade ceramic plate! As you can see in the image, it's not a crack, but rather a design element that occurred during the manufacturing process, a kind of intentional chip?? Therefore, this is for those who understand! Please refrain from complaints such as "it broke!" For those who appreciate the handmade feel. It's thick and sturdy. Approximately 26cm in diameter. For those who understand the current condition.