Well, in Denmark a "real" yorkie must be between 6 and 12 lbs to enter competitions. And from the books I have read on the breed I can read that the only difference from yorkie to silky is size.
I have no clue to the standards in the states, but I do know that the standards of YT is that if it's cute it's a yorkie - and honestly I like that standard much more than any other
