Aussies come in 16 basic color combinations based on body color (red or black), presence or
absence of tan points (copper), and presence or absence of white trim. Within this matrix of 16
basic possibilities there is room for considerable individual variation.
A dog that is only one color (or only merle) with no white trim or tan point pattern is called a self
color. If he is black, he's a self black. A dog that is a merle with no trim would be called a self
blue merle or a self red merle. Dogs with tan points but no white spotting pattern are "body
color" and tan (ex. black and tan). Dogs with a white spotting pattern but no tan points have in
recent years been referred to as bicolors (body color plus bi), but to avoid confusion it would
seem more logical to refer to them as black and white, red merle and white, etc, to specify what
two colors one means. A dog with both tan points and a white spotting pattern is commonly
referred to as a tricolor. With merles using the "bi" and "tri" terminology becomes clumsy. A
normal blue merle with only one trim color, such as white, is already three colors, and a blue
merle with both tan points and white trim is already four colors. Bicolor and tricolor just don't
fit. It would make more sense to simply say "blue merle" and elaborate on trim color if asked.

The action of the merle gene randomly dilutes black areas yielding a dog with a blue and black patchwork
pattern as individual as a fingerprint. The same is true of red merles. There is considerable variation among
the merles in the amount and darkness of the blue areas. Some have a dilute spot or two, though most don't. It
would appear that there are modifying genes that affect how much blue is present. British breeders of Rough
Collies have successfully selected for blue merles that are nearly all blue with very little black. In Aussies there
has been little if any selection for more or less blue coverage, so many litters contain a variety. Sometimes a
blue merle is muddy, brownish, or has a reddish dilute spot. There is no way to tell by looking if he's a red
carrier, and these features are not an indication of carrier status. The red allele is not known to exist in the
Rough Collie gene pool, and breeders of blue merle Rough Collies have to deal with the same off blue hues
and dilute spots. Here are some examples of the variation seen in blue merles. Ideally a blue merle has an
undercoat the same color as the guard hairs. Some have tan or buff colored undercoats, rendering an overall
muddy appearance.

Red merles show all the variation that blue merles do, and some can be surprisingly light in color. There is not
yet a generally accepted term for the merled area of a red merle. It can vary in color from a light champagne
to a sugar & cinnamon mixture to a lighter red. Some are a rich warm sienna red, while others are a cooler
burnt umber or liver red. The merle coverage can vary from near totality to cryptic, just as it does with blues.

Some have generous trim and some have no copper or white trim at all. Both trimmed and untrimmed Aussies
are fully acceptable in the Aussie standard. Self blacks and blacks with minimal white tend to be found more often
in working lines.

Red Aussies result from being homozygous for the red allele, and they can vary considerably in tone and shade
of color. As with red merles, the body color of a red solid can vary from fairly light to so dark that the dog must be
examined in the bright sun to see that it is a red and not a black. The tone can be a warm sienna or a cool burnt
umber. Probably modifying genes determine the exact shade the red will be.