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Black-and-orange cats are called tortoiseshells. Blue-creams are a “diluted” version of black and orange. When white markings are also present, the cats are said to be tricolors, calicoes, or “money cats.” The black-orange (or blue-cream) color-determining genes are linked to the female sex chromosomes. For this reason tortoiseshell males and tricolor males are produced only as the result of abnormal chromosome arrangements that occurred in one or both parents. Such abnormal arrangements often lead to infertility, and the males may not be able to reproduce. In other words, tortoiseshells and tricolors of breed standards are very difficult to produce by controlled breeding.