In order to make a hard boiled egg you are required to put an egg in boiling water at a certain temperature until the yolk within the egg becomes solid.
At this point when the egg is boiled you usually can take it out and shock it in cold water and it will make the shell of the egg easier to be peeled off.
So can gerbils eat hard boiled eggs at all?
Yes, but only small amounts twice at a week at most.
Make sure that you first remove the shell and chop the hard boiled egg into small pieces and give only a small amount.
Something that can be easily held in their paws. Anything larger and they will have issues with it.
Make sure you do not give an egg with runny yolk to your gerbil.