[matese]

I just googled your question, and here is your answer.

Adult Yorkie, Mature Coat
A Yorkie's coat gradually changes for up to two years, and it may stabilize only to change again -- perhaps even into the third year. An adult's hair color can vary from a dark, steel blue to a light, silvery blue. Typically, the black turns blue (a diluted black coloring), yielding a dark steel blue or a shiny silver. Generally, an adult will have more tan and gold coloring, making its coat much lighter than a puppy's.