I have known some parents that have ceramics were stained; we know for sure that this dish is expensive when we bought so how do we give solution if it was stained. I just found this tip in Good Housekeeping February of this year edition. I am sure you will find this tip very helpful you can also spread this tip to your friends.
To get back the former shine of your ceramic dishes, use a baking soda. Mix baking soda to maybe a bowl of water or it depends how many baking soda you are using for your water just you see it forms a paste. Use the paste to scrub your items. Then soak the ceramic dish in vinegar and warm water then rinse or wash it with what you’re normally wash your dishes.
You can also try to mix a pinch of salt and vinegar, and then spread it in the ceramic. Leave the solution to the plate for few minutes or wait until it’s dry. And then wash the ceramic the usual that you are washing your dishes. For cutlery markings, scrub it with toothpaste, for hairline cracks, soak it with warm milk, and leave it for a night and wash.