This is Gres, which is much harder than normal ceramic. In fact, it is for professional use, for restaurants and places where it is used very frequently and in adverse conditions.
These pieces can be put in the oven, microwave and dishwasher without any problem; it never cracks or splinters, it is very durable and resistant.
They only make useful products with little decoration. Everything is handmade, therefore any piece can be made in the size you want and even with a specific shade, if the quantity is large enough.