For adult Teacup Yorkie or Yorkshire terriers, the importance is placed on its coat color, its quality, and its texture. The hair must be glossy, fine, straight, and silky. Traditionally the coat is grown-out long and is parted down the middle of the back, but must never impede movement.
Teacup Yorkies have very soft coats. Yorkshire Terriers have two types of coats; a silky or a soft coat. The silky coats are the coats of the show dogs. The soft coats are short and do not need to be brushed very often.
From the back of the neck to the base of the tail, the Teacup Yorkie coat should be a dark gray to a steel-blue, and the hair on the tail should be a darker blue. On the head, high chest, and legs, the hair should be a bright, rich tan, darker at the roots than in the middle, that shades into a lighter tan at the tips. Also, in Teacup adult dogs, there should be no dark hairs intermingled with any of the tan colored fur.
Adult Teacup Yorkies that have other coat colors than the above mentioned, or that have woolly or extra fine coats, are still considered to be Yorkshire Terriers, and will be just as good of a companion as a dog with the correct coat.