Wow he is so gorgeous, I'm sure he have a violet factor but I'm not sure if it's DF or SF. But even if he is a SF he will have violet babies, violet is dominant. I recommend you to breed him with a blue violet hen budgie, you would have amazing violet colors from they?
I've heard it's possible to have the violet factor and the gray factor in a budgie, but I haven't seen any photo.
These budgies take just one of the 2 factors in their color and we just know they had the other factor too when they have babies? Or we can see both factors (visually) in a budgie??
Because of his cheek patches maybe he is a sky blue with violet factor, they are like cobalt blue but mord bright. If you could take a picture close to their cheek patches and his chest would be better to identify him