There is no such thing as a Tea Cup breed of Yorkshire Terrier.
A yorkie is a yorkie. A Yorkshire Terrier can range in size from over 7
pounds to the smallest we've personally seen of 1.5 pounds. However,
as a long time owner of these tiny souls, we acknowledge that the term
"Tea Cup" generally refers to the smallest of these pups, under 4
pounds full grown.
"Tea Cup"
Yorkshire Terriers