The Cavalier King Charles Spaniel breed was recognized by the American Kennel Club in 1995. They are friendly little dogs, eager to learn and easy to train. The Cavalier King Charles has four color varieties accepted by the AKC. To figure out a puppy's future coat and pattern colors, you must consult a table. But there are some basics that will help you understand the color varieties.
Identify your Cavalier King Charles spaniel colors. According to the AKC, Blenheim is "Rich chestnut markings well broken up on a clear, pearly white ground. The ears must be chestnut and the color evenly spaced on the head and surrounding both eyes, with a white blaze between the eyes and ears, in the center of which may be the lozenge or "Blenheim spot." Tri-colored is black, tan, and white with specific areas where each color may be. Ruby is a solid red, but if it is a show dog it cannot have any white patching. Black and tan is self-explanatory. Sometimes a black and tan will have some white patching which is considered a fault for show dogs.
Consult a genetic color chart to figure out what role genetics play in deciding the coat color of your Cavalier King Charles spaniel. It is difficult and complicated, but once you understand how the dominant and recessive genes work, you will be able to figure out what part genetics play in determining the coat colors of a Cavalier King Charles spaniel. See resources for a genetic color chart.
Keep in mind that recessive genes, including color genes, can "lurk" unknown for a very long time before expressing themselves in puppies, so the more dominant colors/patterns of Cavalier King Charles Spaniels might very well be carrying the most recessive. The puppies inherent four genes from the parents. Two (one from each parent) are concerned with determining the puppy's coat color, and two determine patterns.
Ask a Cavalier King Charles breeder or registered AKC show judge if you are still unclear after consulting the coat color genetics chart. They have experience in breeding for colors and patterns and will have the best and most current information. Ongoing research into genetics identifies new genes all the time, so it's best to check with an expert if you are still unsure about understanding color coat genetics.