Over the years, there have been accounts of pure silver Persian kittens turning to a pale golden colour as they mature. This often began with yellowish "tarnish" or cream spotting appearing in the coat of a shaded silver or chinchilla cat. Reddish hairs first appeared on the spine, face or paws, and progressed through a yellowing of the undercoat. Chinchillas derived from chinchilla-to-chinchilla matings sometimes exhibited reddish or golden hair along their spines which was attributed to incomplete dominance of the golden gene "breaking through" in the coat. Some silver kittens were, when 2 or 3 years old, very definitely pale golden adults. Offspring born to such cats were born as silvers, showing the "golden" cat was genetically a silver, but some of those offspring also had a tendency to turn golden at about 2 or 3 years old.
Silver and chinchilla cats have been selectively bred to eliminate (as far as possible) polygenes that would modify the colour's purity. The silver should, therefore, be devoid of genes that cause cream, yellow and red pigment. Yellow denotes the technical term for the pigment granule which produces all of these colors. Polygenic complexes have plus and minus polygenes that influence the trait. Diligent breeding resulted in accumulations of either plus or minus polygenes in a specific breed or colour. However, these polygenes are carried on different chromosomes and inherited independently of each other.
In silvers, the inhibitor gene means the round granules of eumelanin (black) are absent from most of the hair shaft and are clumped near the tip. Being incompletely dominant, the effect ranges from shaded silver through to tipped (chinchilla). In normal goldens, the granules of the yellow pigment phaeomelanin are likewise influenced by the inhibitor gene. However, the silvers that turn into goldens don't have any phaeomelanin. Instead, these "pseudo-goldens" turned out to have an additional mutation that caused their eumelanin granules to be elliptical rather than round and to show as a beige or pale golden colour. These mutant granules are not completely eliminated from the hair shaft, but are smeared along it, causing a pale golden undercoat. They are also clumped at the tip to give the shaded or tipped effect.
Eumelanin is usually described as "black", but is actually a deep brown (sepia) that appears black to our eyes. As the eumelanin granule becomes elongated, it appears paler and more reddish-brown or dark-yellowish-brown. The concentration of the mutant eumelanin granule on the hair shaft gives colours ranging from copper-brown through apricot to reddish honey, all with darker tips. The mutated eumelanin gene has been described as a "late colour change" gene for obvious reasons. Its mode of inheritance not fully understood. It is also possible that some apparently golden-from-birth Persians may be pseudo-goldens and can have silver kittens - generally considered an impossibility as silver is dominant over normal golden and cannot be carried as a recessive (though silver can reoccur as a spontaneous mutation).
A "late colour change" mutation, again causing an end result of golden, has been observed in Norwegian Forest Cats. The Black Modifier gene, found in Norwegian Forest Cats, brightens black or blue areas of the coat to Amber (apricot-to-cinnamon colour) and Light Amber (pale beige). At birth, kittens appeared to be black or blue, and lightened to Amber or Light Amber respectively. Amber has also occurred in conjunction with silver: the kittens were born as poorly coloured black-silver or blue-silver tabbies whose tabby ghost-markings faded as they matured and their colour became a bright apricot to cinnamon colour with dark brown paw pads and nose leather with no black rim (the black rim is characteristic of silvers). Their original birth colour could be seen only on the back and tail.
This Norwegian Forest Cat was bred by Yve Hamilton Bruce from a silver mackerel tabby female (imported from Denmark) and a classic red tabby and white male. The result was 1 silver tabbies and 2 silver tabbies with white. At just over 3 months old, this silver and white tabby male developed a large patch of bright red hair on his back. Eventually the whole fur will become amber. The effect of amber during the colour-change stage depends on the original colour - solid black or blue, bicolour or tabby.