After the base colours, the dilutions are the best known horse coat colours. They are part of the modifier group, but often showed separately due to their striking results and common behaviour. All dilutions alter (lighten) the entire coat and/or the points (mane, tail, ear tips, lower legs) of a horse. Some may also influence skin colour.
Horses with the diluted colours, have both been despised and loved in history. In some cultures, the lighter colours were seen as a sign of weakness, while others praised the unique variations. In modern time, dilutions seem to be growing in popularity again.
CreamCream is probably one of the best known and most popular dilutions. When combined with the base colours, it is responsible for palomino and cremello (on chestnut), buckskin and perlino (on bay) and the varieties smoky black and smoky cream (on black). When combined with other dilutions, like dun, new unique names like dunskin (dun and buckskin) and dunalino (dun, palomino) are commonly used.
This dilution is incomplete dominant, meaning it has a different result in heterozygous and homozygous state. In heterozygous state, it dilutes the red pigment of the coat to a yellow-gold. Black pigment remains largely unaffected. When two copies of the cream gene are present, the hairs of both the coat and the points become a creamy white, no matter the original pigment.
The cream gene has a second dilution attached: pearl. Though probably very old, it was only recently identified and appears to be linked to an Iberian origin. Pearl behaves as an incomplete recessive. One copy of the allele brings about such little difference (though experienced breeders claim they can see it), it is often dismissed. Two copies result in a colour that is a little similar to a single cream dilutions, but with the unique pearl sheen.
Pearl also interacts with cream. When one copy of each is present, the horse's coat is diluted to a cream colour that is somewhere between a single cream dilute, and a double.
The champagne colour is similar to the white pattern called frame, as it seems to have a recent American history.