My Zoe' still has some black with her silver (2 years old). Some do not turn completely silver. The top of the saddle (or back) is sometimes lighter then underneath. My aunt had a yorkie that lived to be 15 years and her saddle was never completely silver, always some black but mostly silver on the top. It probably depends on the dogs and they can turn out like their grand parents instead of their parents the way I understand it. Even in size, they may be larger or even smaller then their parents. I have one that is 10 pounds, she is bigger then her mom or her dad was. Her coat and size is starting to stay the same now at 2 years old. The main difference that I see now is that her tan on her head and face is more rich or reddish to me the older she gets. I was told by a breeder that the color deepens with age or maturity.
Telea, Zoe' and baby Mia
