What
few people realize is that the Siamese cat is actually born white
and will develop their characteristics points later, by about 4
weeks of age. The colour of the Siamese depends on a 'pointing
gene' which is a a result of the partial albinism gene.
The “pointing gene” that
the cat is born with is heat sensitive. As the Siamese
grows older, his colder extremities (ears, face, legs and tail)
darken until he has the characteristic coloring of the breed.
A enzyme producing pigment in the cells of the hair root produce
little or no pigment for the growing hair at temperatures above
98°F (37°C).
Anything that affects the temperature
of the Siamese can also affect their point color. For
example, generally adult Siamese living in warm climates have lighter
coats than those in cool climates. Also, a Siamese that is
overweight tends to be darker because the extra layer of fat insulates
the skin from the body, thus causing it to produce more pigment.
A Siamese that has been ill will often show "ticking",
or lighter colored hairs in it's mask because the actively growing
hairs will be un-pigmented in the elevated temperature of a fever.
The pigment also tends to darken as the cat ages.
The
blue eye color of a Siamese is also due to the partial albinism
gene. Siamese have little to no pigment (yellow-brown) in their
eyes and the blue color is actually a result of reflected white
light from the retina. The eye color can range from a pale china-blue
to a deep blue-violet.
Finally, the hair length of the
Siamese is also monitored by a gene. The long-haired
Siamese, or Bali, also comes in the classic Siamese colours
described below. It should be noted that the Balinese do not have
any more hair than a Siamese - only longer hairs! This means there
is no extra grooming involved as they are not like the persians/himalayans
that have a double coat. So there is no worry of matting or having
twice the amount of hair!
There also several "modifying"
genes that can further affect the color and density of the points
and these give us the four classic Siamese colours: seal points,
chocolate points, blue points and lilac points. The seal
points are the best known variety and were the first to be recognized.
Seal points have pale fawn bodies and extreme almost black points.
The chocolate points came second with creamy white
bodies and milk chocolate points followed by the blue point
that has a bluish-white body with slate blue points. Last was the
delicate looking lilac point with a white body and pinkish
grey points. Other more recently introduced colours include the
red and tortie point.
Seal
Points
Seal points have seal brown, almost
black points with fawn colored bodies. Their nose leather and paw
pads are the same color as the points. Seal points tend to be the
"traditional" color most people think of when they picture
a Siamese cat. This color also seems to have the most variation
in shades. You will see seals that look "black and white",
or you may also see seals that are dark brown over the whole body
and there is very little contrast between the points and the body.
As very young kittens, the point color tends to look "muddy"
and indistinct. At this age, seals and blues look very much alike,
and chocolates and lilacs are also very similar. It takes several
weeks for the colors to be distinct.
Chocolate
Points
Chocolate
points have milk chocolate brown points with creamy white bodies.
Their nose leather and paw pads are cinnamon-
pink.
Chocolate points tend to stay lighter in the body as they age, with
a more noticeable contrast between the body and their points. It
tends to take much longer for a chocolate point to develop their
point color, as opposed to a seal point.
Blue
Points 
Blue points have slate blue (gray)
points with bluish-white bodies. Their nose leather and paw pads
are slate blue. Blue points can get quite dark in the body also
as they age.
Lilac
Points
Lilac points have pinkish-gray points
with white bodies. Their nose leather and paw pads are lavender-pink.
Lilac points are the lightest of the four Siamese colors, and even
as they age will stay very light-colored in the body.
The
Siamese is considered one of the oldest breeds of all our cats. They
are intelligent cats with an inquisitive personality and a loving
nature. Today this ancient breed has become the most popular of all
pedigree cat breeds.