Probably the most common color set is Sable and White or what people refer to as “Lassie” dogs. Variations of Sable and White are “pure for sable” and tri-factored sable” but in addition they can also be “white-factored”.

• Pure for Sable is when the dog does not carry any tri-color gene. Parent color gene inherited on the A locus is Ay/Ay.
• Tri-factored sable is where the dog has inherited a tri-color gene from one parent and so they have a darker sable and white coat. Some people refer to this as a shaded sable or a mahogony sable depending on how deep the color is. Parent color gene inherited on the A locus is Ay/at.
  • White-factored sable is where either the pure sable dog or tri-factored sable dog has also inherited one white gene on the S locus. To make it a little more confusing there are two sets of white genes on the S locus. si/si all collies inherit, known as the irish gene and it gives all collies the white collar, white legs, white feet. On the other hand S/sp inherited makes the rough collie dog or rough collie puppy a white-factored dog.

Merles come in basically 3 shades; blue merle, sable merle and maltease blue merle. The latter of three being the rarest of the merles.

• Blue Merle collie is a dog that basically would have been a Tri-color collie but that dog also carries a dilution gene which breaks up the black into a mottling effect. They inherit at/at, M/m, d/d.
• Sable Merle collie is a sable and white dog that inherits a merle gene and can be either a pure for sable merle or a tri-factored sable merle.  Ay/Ay, M/m, d/d or Ay/at, M/m, d/d
  • It’s worth noting here that two merles should not be bred together as it can produce a double merle M/M which can be blind or deaf or both at birth. 

A tri-color collie is a black and white collie with tan coloring on the face and legs/feet. This collie inherits at/at at the A Locus. Whew! At least that one was easy to descibe!

As well as the 3 basic color sets there are whites. A white collie (inheriting Sp/Sp) or known as piebald, can either be all white or be a “color headed” white and/or have colored body spots. All white collies in my experience are few and far between but do happen. White collies come from either breeding two whites or one white with one white-factored dog. So within the white family: 

• White Merle is a white dog with either blue merle markings or sable merle markings inheriting one merle gene as indicated with one uppercase M.  M/m.
• White Sable is a white dog of either pure for sable or tri-factored sable head and/or body spots.
• White Tri is a dog with a tri-color head and/or body spots.

There are many other possibilites given the different alleles. Some allow express of color and some don’t. 

From our rough collie boys page

Lummi = Tri-factored Sable and he carries a recessive white gene. Ay/at on the A Locus, sp/Sp on the S Locus.

Shep = Tri-headed white and he carries at/at on the A Locus and Sp/Sp on the S Locus.

Dusty = Tri-factored Sable and he is also white-factored so he carries Ay/at on the A Locus and sp/Sp on the S Locus. 

I have permission from iCollie.com to include their image of rough collie colors on my page and so I wish to acknowledge them and provide a link back to their web site. My own information I’ve included is but a small part and they go into much more detail showing results of breeding one color with another and show the expressed alleles, so please give them a visit!