Red (the "b" influence)

Now we will elaborate on the brown, or red colouration from the "B" series. Red (as we will call these dogs from now on) is influenced by the absence of dominant "B", therefore it is expressed as "b". ("bb") As any dogs containing "B" will be black, these red variations are always "bb". Any form of "b" is also known as 'dilution' - therefore "b" is known as the brown dilution gene. In effect, this means that all forms of black on our dog are diluted to a lighter colour - a shade of brown. The result will be predominantly the same colour.

The dog you see here is a Chesapeake Bay Retriever, and is affected by this brown 'dilute' gene. It is recessively "bb" and cannot express or produce any black colouration whatsoever. This is demonstrated by viewing the dog's nose, eyerims, skin, coat, and eye  colour itself.

Here is an example of a 'red' dog's nose colouration. As the entire base colour is now diluted black, every extension is the result of this dilution. The nose is almost the exact colour of the coat and contains no black. Nose colour such as this is often termed 'liver' and is quite prone to suffer from natural effects such as sunburn.

Here is an example of the same kind of diluted colouration - and its effects on the eyerims. Note the clear black rim is no longer present, making the eye also more prone to sun problems.
Here we make a note of the fact that black is the base colour and that, because of this, any alterations to the black alter the entire colouration aspect. This is true of eye colouring as well. Because this dog is affected by the dilution of black to brown, the dark brown eye has also been changed to a very light, rich amber. The pigment is lessened and as a result a startling change in colouration has occured.

Now I will include some examples of variations of this colour dilution.

Dark Red - as seen in this Australian Kelpie - is often described as 'liver' and is the darker end of the scale of red black dilutes. This particular shade is close in darkness to black itself, however it is very apparent that this dog posseses no black pigment. (Nose and skin colour being indicators.) Our dog is not affected in any way by any other patterning, and is basically genetically a solid black dog - but with dilution.
Thus, its phenotype would be "KK" "bb" - because it is obviously brown and does not have any black colouration at all.
Or, our dog could be "Kk" "bb", because Kelpies often come in tanpoint patterning.

Here we have a beautiful example of a 'liver and rust' Doberman Pinscher. Its colour is slightly lighter than that of the above dog, however is still distinctly dark. The dog possesses the same pale nose and brown skin, as well as lightly-coloured eyes. (Green or amber.) This dog, however, has an added pattern of tan points. These points are a dark colour tan, but are not affected by the black gene.
Because of the expression of these tanpoints, the dog's phenotype would be "kk" "bb".
There are no exceptions here.

Now we have the example of a light brown Border Collie; this colour as seen is often called 'Red and Tan'. The dog possesses the liver nose, brown skin and lightly-coloured eyes of a brown dilute dog, and has no visible black. Its red shade is particularly light and this colouring is combined with the tanpoint pattern. The difference between this dog and the above is merely in the shades of colour. The white is affected by a differemt influence, so I shall not include that here. Thus, this dog's phenotype would be "kk" "bb" - again, no exceptions.
These variations in shade also cause some dogs, like this one, to have points a similar colour to or darker than its overall body colour. 

This Border Collie expresses a beautiful dark red/liver colouration as does the above collie; it, however, does not express tan points. Because of this, we can assume this dog has at least one "K" and is therefore "KK" or "Kk". As tanpoint is common enough in Border Collies, it is likely "Kk."
This dog shows the same diluted colouration of skin, nose, eyes and coat.

 These adorable puppies are seemingly all red. Yes, that may be the visual colour, but they are actually geneticallt vastly different and will throw different offspring. The three dark brown pups are dilute blacks. As we know, this is caused by "bb". The three 'red' pups are actually black nosed. Their redness is affected by a different influence entirely. They are actually "BB" or "Bb". This will be explained in greater detail further on.

Ah, some more puppies to look at. I added these two simply to show the variety in shades of red/brown and how their colouration is similar in contrast to the 'rust' of their tan point pattern.
These puppies may darken with age, but they will likely stay that beautiful earthy colour for life.
Their phenotypes would be "kk" "bb".
No alterations.

One thing I will quickly mention now is genetic inheritance. Because these dogs are "bb", a recessive factor, they are not always common. In some breeds, like Labradors, they pop up as a result of planned breeding, but in some breeds the colour being produced from seemingly black coloured parents can come as a surprise. This is, obviously, due to the recessive factors matching up ("bb") and remaining hidden in parents. It is often difficult to tell if a dog is "Bb" if it is always bred to "BB". If, on the off chance, a dog is bred to another "Bb", the breeding may result in a red/liver coloured offspring. The percentage, in theory, is 25% "bb", 50% "Bb", and 25% "BB". (75% black.) If one of these chocolate dogs was bred to "Bb" - chocolate carrying black - they would have red/liver offspring. If our red/liver dog "bb" is bred to a dominantly black dog "BB", no coloured offspring would result. This is explained in the labrador punnet squares.
Next we will look at Black III ("D") and black in its second dilute form: Blue.