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 dilution affects both red and black pigment. Red hair becomes gold, while black hair is diluted to a more chocolate brown, often best described as the colour of a Weimaraner dog. Often, a bright iridescence gives the coat a beautiful metallic look. The skin colour ranges from pink to lavender, with dark freckles. Eyes are amber or hazel.
Foals are born with blue eyes and a much darker coat colour, which lightens quickly. Their skin is more pink, with freckles only appearing in abundance as they age. Homozygous horses are nearly impossible to distinguish from heterozygous horses.
Dun is probably one of the oldest dilutions, as many suspect it to be the original horse colour. It dilutes both red and black pigment, but leaves certain areas partially unaffected, resulting in the so called 'primitive markings', including a dorsal stripe, leg barring, shoulder and sometimes neck stripes or shadows, darker ear tips, frosting in mane and tail, a dark face mask, mottling on the upper leg, cobwebs on the forehead and brindling. Not all of these have to be present at the same time. In addition, the coat is diluted to a slightly lighter, more dull colour, increasing the contrast with the darker markings.
Silver dilutes the mane and tails of black-based horses. It can also have an effect on the black of the lower legs, sometimes diluting it or creating diluted areas. The effect is usually more profound in younger horses as the mane and tail may darken as the horse ages, sometimes to a point where they appear almost undiluted.
In foals silver can be identified by striped hoofs and white eye lashes, though these characteristics may disappear as the horse ages. Both can also be caused by other colours, so presence is no evidence in itself.