Hello! I will be buying a yorkie pup soon and I would like some of your expert or experience help

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I have been speaking with this breeder and he told me the mom weight was 6 pounds and the dad weighted 9... I know that is slightly over the standard weight.
Another thing is that all the puppies have white on their chests some more some less... the parents of the puppies don't have white though and the older brother I saw doesn't have one either they all are blue and gold. Please help with that.
Also I would like to know if by the picture I am sharing you can tell me if the pup is a pure yorkie or might be a mix (I make this question mainly because of allergies, I've been around Yorkies and they do not affect me). Also if you can tell by the pic if the puppy will be silky or cotton coated. Thanks in advance!