Siamese cats come in a number of colours. The most common being Seal, Blue, Chocolate and Lilac. All Siamese are known for their off white/cream bodies with darker colouring on their nose, ears and tail. This is due to the Himalayan gene, which causes partial albinism. The gene is temperature sensitive, and is inactive on warmer parts of the body such as the trunk, but is active on cooler parts of the body such as the nose, ears and tail, allowing pigment synthesis on these parts of the body. The Himalayan is recessive, meaning two copies of the gene are required (one from the mother, one from the father). If you mate a Siamese cat to a Siamese cat, the offspring will also carry the Himalayan gene and be pointed.
Many people ask if it is possible to have a black Siamese cat. Genetically a Seal Point Siamese is a black cat, but the Himalayan gene prevents the production of melanin in the hair on the warmer parts of the body, resulting in the pale cream/white colour on the body with darker pigmented areas on the nose, ears and tail.
If you are looking for a true black cat with the Siamese temperament and body shape, then an Oriental would be the cat for you. They are essentially a "coloured" Siamese cat. The cat pictured on this page is a Black Oriental, his father was a Caramel Oriental and his mother was a Seal Point Siamese. As he is a black cat, he is registered as an Oriental. Some of his littermates had the Siamese markings/colouring and were registered as Siamese. Unlike the Siamese, though, you will not have a black cat (Oriental or another breed) with blue eyes. The Oriental's eye colour will be a shade of green.
The Siamese isn't the only breed of cat to be pointed, other breeds include:
If it's not a Siamese, then what breed is my black cat?
If you have a black cat with the long, slender appearance of a Siamese cat, the chances are you have a "mixed breed" cat. These cats can come in all shapes and sizes, some large and stocky, others slender and long. There is a chance that they have some Siamese in their background, but if your cat is black, he is not a Siamese.