Obtain high-gloss oil paint to match the color of the surrounding tile. Most specialized paint shops can create an exact color match from a sample in a few days. If possible, drop off a spare tile at the paint shop.
Wash the chipped tile area with a soapy sponge, removing all traces of dirt, mold and debris. Rinse the area thoroughly.
Dry the repair site with a hair dryer. Once the area looks and feels dry, continue drying for 15 minutes; chipped ceramic tile can absorb water very well.
Apply an oil-based primer/sealer to the chip with a small brush, being careful to keep the primer off of the glazed tile surface. Allow the primer to dry for two hours.
Paint a coat of matched high-gloss oil over the primer, and allow it to dry for 24 hours. If the color is too thin or needs to be changed, apply a second coat and wait 24 hours for drying.
Mix two-part epoxy on a scrap of cardboard. Squirt a small, equal amount of each part onto the cardboard, and mix well with a toothpick.
Drip the epoxy over the painted repair with the toothpick. Add enough epoxy to raise the level of the repair to match the surrounding tiles. Let the epoxy set for 24 hours.