There is no such breed! The Yorkshire Terrier breed standard classifies Yorkies as up to 7 pounds. They may weigh from 4 to 7 pounds. If a breeder or pet store is selling a "teacup" or "mini", run away! They may be shady and misrepresenting the Yorkie. The tiny ones may be sold too early, perhaps just so they can call them "teacups" or a "mini". If you are set on a smaller Yorkie, ask your breeder when their next litter will be. There will be some "smaller" Yorkies in the litter from which to choose from. A respected breeder that is AKC registered. While that does not always determine that they are to be trusted 100%, there are standards and qualifications that AKC registered breeders must pass.
There are small, full-grown Yorkies that may only weigh 2 pounds. But, it is very rare for Yorkies to be that small. If you have a Yorkie that is on the small side of the scale, you must be very careful with them, as they are definitely more "fragile" than standard sized ones and you must take extra precautions with them, such as making sure they don't fall from a high place or that they don't jump off of places.
We will close or delete any For Sale threads looking for or selling "teacup Yorkies".
For more discussion on this subject, see:
http://www.yorkietalk.com/forums/sho...ghlight=teacup