I have heard about the white patches also...although many yorkie puppies are born with a white patch on their chest that changes to gold. Ramsey had a white spot. Rrosenberry has a yorkie...who has quite a bit of white on his chest that never changed.
I don't have a camera here at work to take pics to show you...but Reggie's (a biewer) tummy has ticking...aka freckles.
His tummy is pink with dark freckles, the roof of his mouth is speckled, he has some pink paw pads...and some black ones.