Colors that do not exist in purebreds

Purebred Arabians never carry dilution genes such as the dun gene, nor the cream gene. Because they do not carry any dilution genes, purebred Arabians cannot be cremello, perlino, palomino or buckskin. Arabians also do not the have the "dominant white" (W) gene that produces a true white horse (with pink skin and blue or light-colored eyes).

Purebred Arabians today do not have genes for most spotting patterns, such as pinto or Appaloosa, except for sabino and rabicano. Spotting or excess white was once thought by some to be a sign of "impure" blood, was disfavored by Arabian breeders, and believed by some to be a mark of impurity until DNA testing for verification of parentage became standard. For a time, horses with belly spots and other white markings deemed excessive could not even be registered, and even after the rule was softened, excess white was sometimes penalized in the show ring. Nonetheless, there is pictorial evidence from depictions of chariot horses in Ancient Egypt and some later artwork that suggests that some of these patterns may have existed in antiquity.

To produce horses with Arabian type but coat colors not found in purebreds, Arabians are crossed with other breeds to produce half-Arabians with additional colors.

Thus, though the purebred Arabian produces a limited range of potential colors, there is also a positive side: because they never carry the frame overo gene ("O"), a purebred Arabian can never produce foals with lethal white syndrome. In fact, Arabian mares were used as a non-affected population in some of the studies seeking the gene that caused the condition in other breeds. However, a partbred Arabian can, in some cases, carry these genes if the non-Arabian parent was a carrier.