The short Review of Yorkshire Terrier's Breed Standard

Yorkshire Terrier, although classed as a toy breed (AKC) is descended from terrier bloodlines
The general apperance that Yorkie is a long haired toy terrier whose dark steel blue and tan color coat is parted on the face and from the base of the skull to the end of the tail and hang evenly and quite straight down each side of the body ( the coat must be perfectly straight and not wavy)
The body is neat, compact and well propotioned. The dog's high head carrriage and confident manner should give the apperance of vigor and self importance.
Head is small anf rather flat on top, the skull not too prominent or round, muzzle not too long with the byte neither undershot nor overshoot. Forelegs should be straight, elbows neither in nor out. Hinds legs straight when viewed from behind.
Ear must be small and V-shaped and carried erect and set not too far apart. Tail docked to medium length and carried slightly higher than the level of the back.
Color , quality and quantity of hair is the most important in this breed, color should be dark steel blue , not a silver blue and not mingled with fawn or black color .The rich golden tan on the head and the weight must not exceed seven pounds.

* References Book :
The Yorkshire Terrier Club of Aamerica, Inc by Patricia Scagliotti.
Yorkshire Terriers by Kerry Donelly