Incubation is 18 day from the time she begins to set the eggs. They will usually hatch about every other day. You can check them beginning on day 7 or so after she starts setting tightly. Use a bright flashlight in a semi dark room. Carefully pick up one egg at a time, hold it over the flashlight, not touching it to the light. The heat will kill the embryo if it gets too warm. At 7 or so days you will see red blood vessels inside the egg. Later it will look like a dark clump in it. Dead eggs also look like a dark clump toward the end of incubation time.

There will likely never be just a shell. There will be a yolk and egg white just like a chicken egg.  If you find a cracked egg, you should go ahead and remove it because if it breaks later on it will not smell good. If a live baby was in the egg it will die due to not having the protection of the unbroken shell.  Professional breeders can often patch a cracked egg but usually a novice cannot do it so the baby can be saved. You can certainly try, using artificial fingernail patching material.

Annie

 

Yup, what Annie said. LOL. I'll just add a couple notes.

 

It very common for the first clutch or two to be unsuccessful, but not always.

 

If the parents seem too upset about you handling the eggs, it might be best to just wat and see if they hatch.

 

When candling the eggs, try to keep them in the same position that they were in the nest. Don't rotate then if it can be helped.

 

At the very end of hatching, sometimes the egg is so full it will look dark. Watch  for movement. You can even sometimes hear peeping if within a day or two to hatching. (I don't toss them unless they are very obviously clear, rotten or the parents abandon them. Sometimes bad eggs have the dark clump off to one side rather than centered like a live baby.

 

FYI: A cracked egg that has a live chick in it and the membrane isn't pierced, you can patch the egg with a very light layer of Elmer's white or school glue and a single layer of tissue, covering as little as possible. Watch very carefully as that egg might need help hatching which can be very tricky.

 

If a chick/s hatch, watch to make sure that the parents are feeding it/them well. You will be able to see if there is food in the crop or not.

 

You will need to provide soft "egg food" for the parents to feed the babies.

 

It's a good idea to get someone to show you how to hand feed and keep hand feeding supplies on hand just in case- as sometimes it takes new parents a bit to get the hang of feeding while others take to it very naturally.