Dilute tortoiseshell is a coat pattern, not a breed. The blue-gray and cream patches come from a recessive dilution gene combined with the X-linked patchwork, which is why nearly all dilute torties are female. Most are domestic shorthairs or longhairs, though the coloring also turns up in Persians, British Shorthairs and Maine Coons.
Coat color doesn't predict personality, despite the tortitude folklore. Dilute torties can be timid, outgoing, cuddly or aloof. Most weigh 6 to 14 pounds and live 12 to 18 years, with moderate shedding that calls for regular brushing. In Chicago, where cats spend long winters indoors, a cat's age, energy and comfort with noise will matter far more than its markings.