Each Yorkie it seems by reading the posts definitely had their own personal time frame on the color changing. If I remember correctly, Schatzie was appx. 6 months or so when she began her color change.
She too is very silvery on her neck and down her back with very blondish feet and face. My friends Yorkie (whom I am persistantly trying to get her on YT) is solid black w/ no silver and i think she's just gorgeous!
There has not been any color combination on a Yorkie yet I haven't liked.