Yes, Fancy's coloring is called chocolate blue (grey).
Chocolate blue is a combination of genetic variance that produces a kind of grey that appears to have a tinge of blue in it. You can get a chocolate blue chihuahua from a black and tan, a chocolate, or even a fawn parent. To get a chocolate blue chihuahua, the parents must have a recessive blue gene in their heritage.
Many chocolate blue chihuahuas have dry skin, which may cause their fur to fall off, leaving bald spots (when we first adopted Bella, she had itchy dry skin and bald spots). We give Bella 1,000 mg. fish oil or salmon oil once a day to prevent this problem.
You could purchase the fish oil or salmon oil in 1,000 mg. capsules in drug stores or health food stores. Cut open a capsule, and squeeze the oil directly into your dog's food for both Fancy and Guinness. These oils are rich in Omega 3 fatty acid, and are good for humans too.