Preheat the oven to 150 degrees.
Use the razor blade to carefully maneuver loose pieces of china plaster form inside of the crack.
Place the china in the oven, and leave it in there for about 10 minutes. The heat will help the china expand, widening the crack.
Mix the epoxy and the paint powder. Pour the epoxy into a disposable cup, and then add small amounts of paint powder until the mix is as close as possible to the color of the china.
Stir with a matchstick and spoon.
Take the dish out of the oven, and place it on the cutting board to cool.
Fill the crack carefully using the toothpick.
Mold the modeling wax into the shape of the plate, and then place the dish inside of the mold. Push the mold gently around the repaired area so that it keeps pressure on the repair, forcing the pieces to bond.
Allow the epoxy to dry for several hours, then go back and carefully chip away at any hardened epoxy outside of the crack using the razor blade.