Here are some tips for cooking hard boiled eggs that will give you nice looking eggs without cracked shells or gray yolks.

- Don't drop the eggs into boiling water. This extreme temperature shock will result in cracked egg shells. Instead, put the eggs in the water and then bring the water to a boil.

- Stick a pin into the round end of the egg shell. This end of the egg contains an air sac and as the egg temperature is increased, this air sac will try to expand, this can lead to cracked shells. If you stick a pin in the shell, this allows the expanding air to escape and it reduces pressure on the egg shell. When doing this, make sure you use a small pin (a large hole will allow water into the egg which is bad) and just go through the shell, don't poke through the air sac into the egg white.

- Once the cooking is complete, run the eggs under cool water for several minutes. This stops the insides of the egg from cooking and will give you nice bright yellow yolks without any grayness to the outside of the yolk.