By the way, I don’t know the answer to the question except to state the obvious, namely that the darker fur is longer than the background lighter fur.
In fact, if one looks closely, the embossing is more subtle than that. There is a mass of dense dark fur making the pattern, which is raised somewhat and within that area there appears to be some individual hair strands that are significantly longer than the rest, which poke through. These longer hair strands also appear to be wispier, more like down hair. However, down hair is normally the shortest type of hair in a cat’s coat.
Down hair is the undercoat, which keeps the cat warm. The other layers are guard hairs (at the top) and awn hairs. The guard hairs protect the coat and the awn hairs protect the undercoat. The guard hairs are the longest and they taper from base to end – see cat hair for a full description.
The picture heading the page is of a Bengal kitten, so not yet fully developed. Perhaps the embossing disappears as the cat becomes an adult in the same way that a kitten’s undeveloped eyes are blue until the pigmentation in the iris develops. Is the embossed coat of this Bengal kitten a part of what Bengal cat breeders call the “Fuzzies”. The word refers to the hair of a Bengal cat when he or she is kitten. After 6 months the coat is developed. Young cheetahs also have the fuzzies (see photo below).
Of course, the Bengal cat has a connection with the wild cats: the leopard cat. Does the leopard cat have the fuzzies? I don’t know. Is the embossed Bengal coat inherited from the leopard cat?
The embossed coat is certainly a very interesting feature. I have not heard about this on any other cat breed. That is not to say embossing does not occur with other cat breeds and freeborn cats (random bred cats).