Study the word list: ie words

One of the best known spelling rules is i before e except after c , but does this rule really work? Is it true ALL the time? As with most spelling rules, it works MOST of the time but not always. Take a look at these ie words. They all have

Spellzone list

field	The sheep were let loose in the field.
brief	The instructions were too brief.
chief	The tribe elected a chief.
grief	His death caused terrible grief.
relief	There was great relief at the rescue.
mischief	That child is getting up to mischief again.
niece	My brother's daughter is my niece.
piece	Please may I have a piece of cake?
siege	The castle was under siege.
priest	The priest blessed the people.
fierce	The tiger was fierce.
pierce	Pierce the lid before cooking.
achieve	He wanted to achieve good grades in school.
believe	I can't believe she has married him.
relieved	She was relieved to hear her father was better.
retrieve	The dog ran to retrieve the ball.
diesel	This truck's engine runs on diesel fuel.
hygiene	Good hygiene keeps germs away.