THE BASIC SELF (SOLID) COLOURS OF CATS
Copyright 2002 - 2020 Sarah Hartwell

Genetically speaking, there are four basic self (or solid) colours of cats: black, chocolate, cinnamon and red. All other self colours are modifications of these. Although covered here as a self colour, red is a form of tabby and it is impossible to completely eliminate the tabby markings. Why are there not five basic colours? White is counted as an absence of colour rather than a colour.

Different countries, registries and breeds have different names for some of the same basic colours. Even where the same name is used, there may be different views on what is an acceptable or ideal version of that colour. Colours which appear identical to the human eye are caused by different genetic interactions.

The same colours are called by different names in different breeds. Even in the same breed, the colour may have different names depending on which country the cat comes from and which registry it is registered with. American registries like to add "mink" after the Tonkinese colours whereas British registries use the same name for that colour as is used in the equivalent Siamese or Burmese colour. Confused? Don't worry - there are some cross-reference tables later on!

The jet-black colour you known as "black" is called "ebony" and "ebony tabby" in Orientals, "black" in solid coloured domestic shorthairs, "brown" when it refers to brown tabby domestic shorthairs, "bronze" in Egyptian Maus, "tawny" in Ocicats and "ruddy" in Abyssinians. In colour-pointed cats, "black" is called "seal". In Burmese it is "sable" or "seal sepia" and in American Tonkinese it is "cinnamon" or "natural mink". In the Asian breed (self Burmese cats) it has a breed name to itself "Bombay". Shaded silvers, black smokes and chinchilla cats may look various shades of grey or silver, but they are black cats with silver roots to their fur. Add dilution and it becomes "blue". Modify the dilution and it becomes "caramel". Yet it is still basically a black cat.

Strange as it may seem, all red cats are actually red tabby because the non-agouti gene (the gene that turns a tabby into a self/solid colour) does not affect the way red pigment is deposited. A variety of other genes, called polygenes or modifiers, control the intensity of colour and contrast between markings and background colour. Selective breeding has reduced the tabby markings to produce a cat that looks solid red by breeding from those cats with the least red markings (cats with "low contrast" between markings and background colour). Because the non-agouti gene does not work on the red pigment, red tabby ghost markings can never be completely eliminated and may be seen on the tail, legs and forehead and as a darker region along the spine. Even though red cats are registered as "red self" they are still red tabbies, albeit red tabbies with very reduced markings. Because they lack the polygenes for high contrast between markings and background colour, their offspring also appear to be red self. More information can be found in Robinson's "Genetics for Cat Breeders".

Sex-linked red masks whatever black-based colours are present on other chromosomes, but those masked colours seem to influence the depth of the red colour. This is visible in pedigree cats where the effects of random polygenes have been largely bred out of the mix. Red masking black tends to be a very intense/hot colour. Red masking cinnamon also tends to be a deep, hot red colour. Red masking chocolate is less intense, a more apricot tone. Cream, the dilute of red is also influenced by the masked colour. Cream masking lilac can be a very delicate shade of cream. Cream masking fawn is even more pale, but is warmer than cream masking lilac. In random-bred cats red ranges from “yellow” or “sandy” through to deep red due to the wider mix of polygenes.

The simplest modification of the 4 basic colours is dilution. As the name suggests, this "washes out" the original colour to something paler. This is also called maltesing since the it was first identified in black cats and blue cats - Maltese is term for blue-grey and some of the eary blue cats imported into Britain were known as Maltese cats.

A secondary type of dilution is called the dilute modifier. It only affects already diluted colours. Since it gave rise to the colour "caramel". I have referred to it here as "caramelising" purely to avoid confusing the layperson. Textbooks always refer to it as the dilute modifier.

Black, chocolate and cinnamon are all versions of the same gene. With the exception of "red" which is a special case, genes are inherited in pairs - one from each parent. Some genes are dominant over others and only the dominant one will be expressed (show up). The other gene (the recessive) will still be lurking in the background and can be passed on to offspring. Depending on which pairing a cat inherits, it will be one of those basic colours. The fact that at it may look different depends on many other genes which alter the way in which these three basic colours are expressed.

If it inherits black + black OR black + chocolate OR black + cinnamon it will be black.
If it inherits the dilution gene it will be blue.
If it inherits the dilution gene AND the caramelising gene it will be caramel.

If it inherits chocolate + chocolate OR chocolate + cinnamon it will be chocolate.
If it inherits the dilution gene it will be lavender.
If it inherits the dilution gene AND the caramelising gene it will be taupe.

If it inherits cinnamon + cinnamon it will be cinnamon in colour.
If it inherits the dilution gene it will be fawn.
If it inherits the dilution gene AND the caramelising gene it will be a pink-brown..

Many early caramels were probably registered as fawns or lilacs, probably as poor quality individuals. The colour differences are subtle enough that it may be necessary to check what is in a cat's pedigree to work out the exact colour. To the rest of us, such cats are simply "biscuit colour" and are no less attractive for it!

Red is a different gene to black, chocolate and cinnamon. It is a sex-linked gene which means a female must inherit 2 copies of the red gene in order to show up as a red cat. A male only needs one copy of the red gene to be a red cat. This is why ginger tomcats are more common than ginger females (though contrary to popular belief, ginger females are neither rare nor infertile!). If a female only inherits one red gene, she is a tortoiseshell.

If a female inherits red + red she will be red (ginger).
If she inherits 1 red gene she will be tortoiseshell (red/black, red/chocolate or red/cinnamon depending on the other genes present)
If she inherits red + red AND the dilution gene she will be cream.
If she inherits 1 red gene AND dilution gene she will be dilute tortoiseshell (blue/cream, lilac/cream or fawn/cream)
If she inherits red + red AND the dilution AND the caramelising gene she will be apricot.
If she inherits 1 red gene AND dilution gene AND the caramelising gene she will be dilute tortoiseshell in the caramelised range of colours (though this may not show up very well and may be impossible to identify.)

If a male inherits 1 red gene he will be red.
If he inherits 1 red gene AND dilution gene he will be cream.
If he inherits 1 red gene AND dilution gene AND caramelising gene he will be apricot.

In reds, there are genes for rufism i.e. for the depth of the red colour. This is why show-quality reds are a rich, deep red colour while alley cats are more often marmalade or ginger. Early reds (1880s) were known as yellows; the depth of colour was improved over many generations of selective breeding.

In 1924, a series of breeding experiments between a Siamese female and a tabby male resulted in black offspring that themselves produced tabby offspring. This suggests a gene for black that is dominant to tabby, the opposite of the known behaviour of tabby and black! It is possible that the Siamese female, one of a pair imported from Bangkok, had a mutation for black colour that was dominant instead of recessive. There have been no further reports of dominant black in the cat population. Dominant black is genetically different to the black colour described above, but unless it occurs again its interaction with other genes will remain unknown.

Note: The usual explanation of black (B), brown/chocolate (b) and cinnamon (bl) is that there are 3 alleles of the black locus gene. Chocolate carrying cinnamon can appear as light chocolate in some breeds, but basically there are 3 phenotypes: black, brown/chocolate and cinnamon. An alternative explanation suggests 2 gene loci, each with two alleles. One locus is black/brown. The other locus is a modifer that, when homozygous (2 copies are present), changes black to cinnamon and brown to pale cinnamon. This gives 4 phenotypes: black, brown/chocolate, dark cinnamon/light chocolate and light cinnamon.

An additional type of recessively carried brown colour was reported in laboratory cats in the USA in the 1960s, but not in the outside world. Termed "Barrington Brown", a cat with two copies of this gene has black diluted to deep mahogany brown, chocolate dilutes to light brown and cinnamon dilutes to a pale cafe-au-lait. There are suggestions it may have been the caramel gene, but the descriptions of the colours quite different. The confusion seems to stem from the discovering describing the light tan of the Barrington Brown cats as "caramel coloured". Barrington Brown cannot be the same as caramel because Barrington Brown affected black and chocolate, but caramel only affects blue, lilac and cream.

The Dilute Modifier gene was posited by Patricia Turner who erroneously believed it to be the same as the Barrington Brown gene reported in a colony of laboratory cats. In essence, caramel lightens and gives a brownish cast to the underlying colour. How can adding brown make something lighter? Brown (in terms of colour, not genetics) comes in a variety of shades ranging from fawn to chocolate and adding a brownish hue is not the same as mixing paint. With the dilute modifier, blue becomes caramel, lilac becomes taupe (brownish grey) and red becomes apricot. In practice, these colours may only be visually distinguishable from each other by knowing the cat's genetics. Some find caramel cats resemble golden series cats and suggest that a theoretical hypostatic (hidden) silver/golden gene is showing through, especially in the lighter colours where there is nothing to mask a hidden silver/golden colour.

In the past, the Dilute Modifier has also been called “double dilution” and “caramelising”. Some people are still not convinced about caramel because almost identical colours can result from blue + caramel and from lavender/lilac + caramel. With a modifier gene, it is possible to get the same end colour (visually) from 2 different base colours (genetically). It depends on what the Dm gene is modifying (the expression of a protein) which is different from mixing paint. Two different original proteins (relating to melanin production or deposition) could be modified by such a gene to produce almost identical expression.

EXTENSION GENES (BLACK MODIFIER) - AMBER/LIGHT AMBER AND RUSSET

The Extension gene (formerly the Black Modifier gene) brightens black areas of the coat. At birth, kittens appear to be black or blue (it has not been found in combination with other genes recessive to black), but become brighter as they grow. The Black Modifier has so far only been observed in the Norwegian Forest Cat. Recognition of the colour by registries will allow the cats to be correctly registered and distinguish them from chocolate, lilac, cinnamon and fawn (not found in Norwegian Forest Cats).

During the 1990s, some purebred Norwegian Forest Cats in Sweden produced chocolate/lilac and cinnamon/fawn offspring. Because these colours are not recognised (they indicate outcrossing) they were called "x-colours". Crossing a "cinnamon spotted" x-colour with a fawn Somali produced blacks and blues, not fawns. Some x-colour cats were registered as "golden", but the x-colour can be found in combination with silver (x-colour silver tabbies), ruling out golden: a cat can be either silver or golden, but not both. The offspring of an x-colour "cinnamon spotted" and a chocolate point Birman were black and blue tabbies, ruling out the recessive chocolate, lilac, cinnamon or fawn and ruling out a recessive masking factor (i.e. that found in colourpoint cats). To produce black and blue offspring, the x-colour must be genetically black (dominant to chocolate). Further test-matings upheld these conclusions.

Self (solid) x-colour cats were born as poorly coloured black-silver or blue-silver tabbies. Their tabby ghost-markings faded as they matured and the colour became bright apricot to cinnamon colour with dark brown paw pads and nose leather with no black rim (a black rim is characteristic of silvers). Mating a self x-colour cat to a black-and-white and mating two self x-coloured cats together showed that the colours were not agouti (not ticked), but were new colours, now called Amber and Light Amber. Kittens are born dark and undergo a period of extreme brightening of the black/blue areas as they mature. Their original birth colour is often seen only on the back and tail, allowing amber and light amber to be distinguished from one another.

Amber is apricot-to-cinnamon colour with brown paw pads, nose leather and eye rims. Kittens are born dark or black, with ghost markings, and brighten as they mature. Light Amber is a pale beige colour. Kittens are born blue and brighten with age, becoming pink-beige to fawn at maturity. The nose leather, eye rims and paw pads are dark blue grey. (To complete the description of amber/light amber: Amber Tabbies are born apricot with black markings; the markings brighten to reddish-brown/cinnamon at maturity. The nose is pink and the paw pads and eye rims are brown. Light Amber Tabbies are born beige with blue tabby markings; the markings brighten to pink-beige/fawn at maturity. The nose is pink and the eye rims and paw pads are blue-grey. Amber/light amber replaces black/blue in torties. Amber also occurs with silver and in bicolours/tabbies -and-white.)

The provisionally named Russet Burmese is an experimental Burmese colour in New Zealand. In 2007, Nicki and Bob Mackenzie's line of seal (brown) Burmese (carrying dilute and chocolate) produced "odd-coloured lilac" kittens which gradually lightened as they grew, progressing through chocolate ticked tabby to red. The kittens traced to the same father and two related females (mother and daughter) and all three shared a common ancestress only a few generations back. DNA testing showed the russet kittens to have the standard seal or standard chocolate genes, meaning there is an a different gene causing the colour change. Russet kittens also tended to be larger than their littermates, both at birth and as adults. Russet appears to be a recessive gene from a spontaneous mutation. It causes the black pigment (eumelanin) to gradually fade to almost nothing while leaving the red pigment (phaeomelanin) unaffected. Like the amber colour change, it might be an extension gene mutation.

Russet kittens have pink noses and paw-pads and a pale tail-tip. The muzzle and fur aroundthe eye is ivory. The back is solidly dark rather than ticked, becoming pale ivory halfway down the flanks. The back becomes more ticked appearance as kittens undergo the colour change and the face becomes reddish. By age two, they may resemble a red Burmese. It differes from amber (in Norwegian forest Cats) as ambers have dark noses and paw-pads. Non-agouti (solid) amber kittens are very dark with a dark face that is last to go red while russet kittens have off-white faces (possible due to Burmese sepia gene in the mix), which are the first part to go red, and pale undersides. The russet colour change appears to be slower than the amber colour change.

PINK-EYED DILUTION

The type of dilution seen in cats is blue dilution (it dilutes black to blue). A second type of dilution seen in many mammals is "pink-eyed dilution". Pink-eyed dilution is characterised by a pink or ruby glimmer to the eye (depigmentation). The coat colour is often diluted to bluish-fawn and the pink-eyed dilution factor is generally inherited as a recessive gene. A possible pink-eyed dilute female cat was reported in 1961. She was described as pink-eyed with a light tan coat. She was mated to a chocolate point Siamese and produced three tabby kittens 10 days premature. Sadly none of the kittens survived. The colour of the kittens implies that pink-eyed dilution in cats is inherited as a recessive trait and is independent of the colourpoint genes. The pigment granules in the hairs of pink-eyed dilute cats were very small and yellowish brown,instead of the normal dark-brown or black. (Todd NB: A pink-eyed dilution in the cat. JHered 52:202, 1961.27.)

ALBINO, DOMINANT WHITE, WHITE SPOTTING

Albino is generally thought of as pure white, but the situation in cats is more complex. There are five known alleles for albinism: blue-eyed albino, pink-eyed albino, Burmese pattern, Siamese pattern and full colour (non-albino). Full colour is dominant to all of the other four alleles. Burmese pattern is incompletely dominant to Siamese pattern; cats that inherit one of each of those genes will be intermediate in pattern and is known as Tonkinese. A quirk of the Siamese form of albinism is that it is temperature dependent with warm areas of the body being paler than cooler areas. For this reason, it is often described as "colour restriction" rather than albinism. Pink-eyed albino appears to be recessive to all of the other albino mutations.

The albino cat reported in Europe and the USA seems to be intermediate between pink-eyed albino and blue-eyed albino. Although it has the white coat of a true albino, its eyes have ruby red pupils and pale blue irises. A true pink-eyed albino was reported in 1931 and again in 1980s in the USA. Albino kittens have turned up more recently in the Bengal breed, unsurprising since albinism is found in the Asian Leopard Cat (the wild parent of the Bengal).

Dominant white is the colour associated with deafness in cats. Dominant white masks all other colours and cats may have blue, orange or odd eyes. Those with blue eyes have a high chance of deafness. Those with one blue eye have a high chance of deafness on the blue-eyed side. Those with orange eyes are far less likely to be deaf. Some dominant white kittens are born with smudges of coloured fur on top of the head, this smudge of colour usually disappears by adulthood, but kittens with colour smudges are more likely to have normal hearing.

The gene for white spotting can also create the impression of a self white cat. This gene is semi-dominant and is variable in the way it is expressed - a cat may have no visible white spots or may be wholly white and all stages in between those two extremes. Unlike dominant white, white spotting is not linked to deafness.

Another form of modification is colour restriction. This is seen in colourpointed cats where the colour is restricted to the head, tail and legs (plus scrotum in males). This is a form of partial albinism. As well as restricting where the colour will be exhibited, it tends to "bleach out" the colour to a greater or lesser degree depending on the type of colour restriction. It may seem odd to think of these as solid colour cats, but genetically they are; they have just had a "special effect" overlaid on them.

There are three colour-restriction patterns:

In the Siamese (Himalayan) pattern, there is maximum contrast between the points and the body colour.
In the Burmese, there is the least contrast but just enough to be able to see that the cat is not a single solid colour.
In the "Mink" Tonkinese, the effect is moderate.

The self colours may have different names in these cats. Alternatively a colour which appears identical to one of the solid colours may be genetically different because of the mild to moderate bleaching effect. A seal-point Siamese may appear to be brown, but genetically it is black!

In Abyssinian and Somali cats, the agouti gene causes the colour to be distributed in bands along each hair. This creates a ticked effect. The most confusing aspect is "red". The bright red colour in sorrel Abyssinians is really cinnamon. The dark red of the Usual Abyssinian is genetically black. Where registries recognise the sex-linked red and sex-linked cream colours the colour name is prefixed by the words "sex-linked". In the USA, the sex-linked colours are apparently not recognised to avoid confusion with the sorrel and fawn colours. To the naked eye (or without the benefit of a pedigree chart), the colours are practically indistinguishable.

It has been thought there were 2 different shades of sorrel red: a bright coppery red and a dark red characterised by an influential American Abyssinian sire called Champion Dhmahl's Diablo. Some pale kittens darken to red, while others become deep solid-looking red with minimum ticking. The dark red is more likely to be chocolate. Chocolate and lilac, along with the silver series, are considered alien to many North American breeders, but are familiar in Europe.

The colour can also be restricted to the ends of each hair. This is caused by a gene for silver. Chinchilla (shell) is the lightest form of tipping or shading - hair tip is coloured and hair shaft is silver, giving a sparkling appearance. Shaded is the next degree - the colour extends further along the hair shaft, darkest on the back (where fur is longer) to create a mantle of shading. Smoke is the heaviest tipping - the undercoat colour is reduced to a small band near the hair root so that the cat appears to be solid colour with a pale ruff until the coat is parted and you can see the silver roots. In goldens, the effect is similar except that the hair shaft is gold rather than white. These cats are still self colours, but the colour distribution has been modified!

There is another effect known as silver-tipping; this is the sparkling silver tips to the otherwise black fur of Chausies. It is an effect inherited from Jungle Cats (F chaus) and is seen in purebred melanistic Jungle Cats. Affected cats are self coloured, but with a modifier which is new to domestic cat genetics.

The previous sections dealt with solid colours and how they are affected by two types of dilution, three types of colour restriction, agouti ticking and silver/golden shading.

There are genes which control how evenly the hair is coloured i.e. the bands of colour on each hair. In agouti cats, it is easy to see different bands of colour using a magnifying glass. In cats with apparently solid-coloured fur, you would need a microscope. Even though the effect on an individual hair can't be detected, the overall effect on an area of fur is make the colour more or less dense i.e. darker or lighter.

In general the self colours (with plain English descriptions) are:

In all likelihood, there are many other genes which subtly alter the colour e.g. by modifying the hair structure slightly to change the way it absorbs or reflects light or by affecting the distribution of the pigment granules in the hair shaft. The appearance of silver-tipped black cats suggests that hybridisation is going to introduce new colours and effects into domestic cats.

Some colours which have already appeared are still disputed. For example "caramel" is a subtle form of dilution. It does not affect non-dilute colours (black, chocolate, cinnamon), but it changes the appearance of already dilute colours (blue, lilac, fawn). Caramels which are genetically blue cats have a brownish cast while those which are genetically lilac are lighter in tone. So should they have separate colour names e.g. blue-caramel (caramel), lilac-caramel (taupe) and fawn-caramel or should all the slightly varying colours be lumped under the name "caramel". They jury is still out on this one, but it demonstrates the importance of knowing what colours the cat has in its pedigree!

Another new colour, indigo, is described as a richer, darker version of blue. This suggests some sort of intensifying effect acting on diluted colours. However since blues can be variable in hue, there is no confirmation that indigo is due to a specific gene or that it is genetically heritable. The only example I have seen depicted a tortoiseshell cat with blue-black and hot cream patches i.e. to richly coloured to be blue-cream tortoiseshell, but not a red-black tortoiseshell. This could mean a gene with the opposite effect to caramel i.e. it acts on dilute colours only, but it intensifies them. If so, it is probably invisible to the naked eye and only noticed in individuals with the most extreme effects of that gene. The same gene would have no discernible effect on non-dilute colours since there are already at their most intense. Note: since other breeders describe indigo as a darker version of blue, the "blue-black" may have been exaggerated by lighting.

If there is a colour intensifier turning blue into indigo, it could be expected to work on the other dilute colours as well e.g. turning lavender into deep lavender, fawn into rich fawn and cream into rich cream. The differences would probably be too slight to be visible - it is already hard enough to detect the caramels!

According to Inina Sadovnikova, "I believe every breeder has had cats of one and the same colour, but of a different shade. Take a black (brown) tabby, for instance. They range in shades from a light grey with a black pattern to a rich brown with a black pattern. Reds are also very different, from a ginger to an intensive orange. The same concerns blue, I have seen blues so dark that one doubts if they are really blue and not black. From my experience, I tend to think that there is a modifier, though I don't know of any studies of this factor. The litters of my female Konkordia always had at least one kitten coloured intensively, either a very dark black tabby or a very dark red tabby. She has a light shade of colour, but her grandmother is darker and also had several dark kittens in her litters. This looks like a recessive, but one needs a lot more of statistics to prove if and how it is inherited. A dark shade is desirable for red, but at present undesirable for blue. So I don't know if "indigo" has any future."

ODDITIES

Strange as it may seem, in some animals the mother's diet can affect coat colour. Recent work at Duke University in Durham, North Carolina, has shown that in a certain strain of mice, the "agouti" coat colour gene can be turned off through methylation. The extent of methylation was dependent on the mother's vitamin intake during pregnancy. (Methylation turns off genes by chemically modifying them). The effect has not been observed in cats, but in theory it could turn genetically agouti (ticked) cats into solid colours.

Some cat shelter workers have noticed apparently self red kittens turning into black adults. Solid black is known to be prone to rustiness through damp or sunlight and evidently, in some cases, to conditions in the womb. Self black kittens are often "rusty" at birth, though few cases are as striking as that of a ginger kitten called "Marmalade" who was entirely black at 6 months old (personal correspondence).

A better documented oddity is that of apparently self red or self black female cats that are genetically tortoiseshell cats. In rare cases, one colour predominates to such an extent that the other is represented by a few isolated hairs.