Mutations
Normals
Normal Cockatiels always are a dark Grey. The Males when they reach 6 months of age will get a beautiful Yellow Face the Females will have a gray face that has a light yellow cast to it.
Pearls
Pearls are also a Sex Link mutation. I love the Pearl mutation when mixed with White Face, Pied and Cinnamon.
Lutino Pearls are very beautiful with there dark red eyes and the vived Yellow Pearling. What makes a pearl is the spot or pearling on the body and wings of the birds. Now the Male will lose the pearling around 6 months of age and will look like a
NORMAL. That is why we should band all babies and keep records of there parents and them.So we know what they came from and what they really are.
Lutinos
Lutinos are a Very Light Yellow Almost White With bright RED eyes. A lutino is a sex link mutation. Whitch means if the male's mother was a Lutino but not his father then any Lutino baby he has is a HEN. The only way to get both Lutino Male and Female chicks is to have a Lutnio Male and Female. Also Sex link means a Female can NOT be Split to this mutation. She is eather a visual or she is not. A hen can NEVER be split to LUTINO.
Pieds
Pied are a striking Yellow and Grey bird. If you get a heavy Pied whitch means that it has more Yellow then Grey on it body it is a very beautiful bird. The Pied on this bage is a heavy Pied. The Pearl Pied is a very beautiful bird too. A Clear Pied looks like a Lutino BUT has NO RED eyes. A Clear Pied is a solid Yellow bird.
Cinnamons
A Cinnamon looks like a normal but is a Brown color insted of Gray.
Cinnamons are
ALSO a sex link Mutation.When a cinn is combind with the White Face it soffens the Brown even more. a White Face Cinnamon is a beautiful bird.
Fallows
Fallows are a Nice soft brown color a little lighter the the Cinnamon But Fallows Have Pink eyes. What I mean is that they are not as RED as the Lutinos eyes. Now it dose get confusing if you breed a Cinnmon split Lutino male to a cinnamon hen and get Cinnamon Lutinos and then you also have Fallows they do look a lot a like then but if you band AND  keep stricked records then you can tell who is who. To tell a Cinnamon from a Fallow look to the eyes. And remember Pink Fallow, dark eyes Cinnamon
White Face
White Faces are a very good looking birds. They look like Normals but have White where the Yellow is supose to be.
Now a White Face can be added to any other Mutation to add carectur to that mutation.
Albinos are really White Face Lutinos. They get the Red eyes from the Lutinos and the White color from the White Face.
They are also Sex Link just like the Lutino. To produse a White Face Lutino the male MUST be split to Lutino and White Face or a visual White Face. The Hen has to be a White Face or Split to White Face.
Silvers
Silvers are lighter grey color then the Normal. Now This is also a Mutation I am not working on yet. There are two forms of Silver that are out there. The Ressecive or RED eyed Silver is a very light silver color. Very striking bird when you add
White Face to the Mutation.

Then there is the Domonent Mutations. There are TWO Domonent forms, Domonent Double Factore Silver and then the Domonet Singale Facture Silver. I am not good at exsplaning the differance but I can tell you on the Domonent birds it does not matter what you breed the bird too you WILL get a Silver Cockatiel out of the pairing.
Olives/Emerald
Emerald are Olives differant breeders call the same bird by one of these two names. The way the yellow and the gray mixs make the Feathers look green. Also this mutation has a scalip look to the feathers like it should be a pearl but it is NOT a Pearl. You would just have to see a picture to understand what I am talking about. They are nice looking birds but I do not have exsperance with this mutation.
Yellow Cheeks
Yellow Cheeks are one of the NEWest Mutations out there. There are two forms of this Mutation Sex link and Domonent Yellow Cheek. The Sex link is just like the Lutino,Cinnamon,Pearl If you have a male that is split to that mutaion then any visuals in that cluch will be HENS.
The color of the cheek patch is what got it it's name it is a nice Yellow color insted of the dark Orange cheek patch. The Domonent Yellow Cheek is just like to Domonent Sillver if you beed it to any bird you WILL get a Yellow Cheek in the cluch.
Pastels 
Pastels look just like the other birds but their Cheek patches are a peach color not orange color. The Mutation is a resesive to White Face witch means the White Face is Domonent. So there will be No Pastel in the cluch. I think the bird can be split to Pastel but not White Face or can be a Normal Bird but be split to only one of these mutation but NOT both. I am still tring to find more infermation on this mutation but not very many people breed them so it is hard to find.
Most of these mutations can be found in books or you can go to the Ameracan Cockatiels web site or National Cockatiels website to learn more. Also there are some great yahoogroups out there that talk about Cockatiels on care,health,cages,and Mutations. Look for CockatielCastel. I am on that one the most. There are some breeders on there that breed the Silvers,Yellow Cheeks,and Emeralds.
If you have questions please do not hesitat to ask.
Click on Mutation Name for Pictures of that Mutation.