Just in case, the ceramic casserole you are referring to is an Emile Henry. I have an Emile Henry FLAME
ceramic casserole/braiser that can be used on the stove/hob without a difuser. It is very good for this application and for the oven as well and performs equal to cast iron, with the advantage of being lighter.
See attached link for a picture: Emile Henry Red Braiser - Cooking.com
Perhaps this may help you.