This is Yogurt, he/she, I have a feeling he is a he, he's about 3-4 months old. His cere hasn't really changed color. I believe him to be a green based dilute, I'm wondering if the cere remains pinkish in male dilutes, or turns blue? Thanks

Also, if anyone thinks him to be something other than a dilute, please let me know, thanks

All males get a blue cere except for recessive pieds, albinos, lutinos and dark eyed clears.
Your sweetie appears to be a hen by the white colour around the nares

Thanks, "she" is alot smaller than the rest of my budgies, are there actual "runts" in a clutch, is she likely to grow much more, being approx. 4 months old already?

She's a hen.

As for mutation, take a look at this site: https://www.****************/colorsguide.html#dilution. Your sweetie looks like the bird on the left. I'm guessing she's a sky blue YF2 greywing.

Dean? Nev?

Thanks, you can't really see it in the picture but at first I thought her tail appeared to be dirty, and it does, but its not dirty, it actually has a brown/dark grey tinge to it that looks dirty compared to her body colors. Whether or not that helps in determining color mutation. Is there such mutation as a cinnamon dilute? Thanks

Your bird is a type 2 yellow face greywing sky blue female

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Thanks, will she change with molting, her body is definitely a pastel green color right now.