How to fill in a chip on a china cup.

if it is expensive China, have it done by a professional.

I would not recommend that, because the chip is now porous and bacteria invades the porous material. Using it for food or drink once cracked or chipped is not advisable.

Chips are usually repaired by grinding the edge of the cup down until it is smooth like the rest of the edge. I don't know how you would do it yourself, but there are china repair places that will do it for you.

my Fiend showed me to use a nail file to smooth the chip. It works great. Then use a tiny amount of tile poxy. Next paint to match with delta paint. Next use clear nail polish to cover after the paint and poxy are dried. I hand wash the China piece after each use.