The Briard comes in many shades of tawny, black, and gray. It is okay to have more than one color on a dog, provided the change is gradual. Color changes with the age of a dog, sometimes dramatically.
Tawny Briards can be almost white, a honey color, a very deep reddish tan, or any shade in between. They can have varying degrees of masking or overlay of darker tawny, black or gray. The change must be gradual, or the dog is considered a bi-color, which is not desirable. A Briard can also be fairly "clear" (the coat is one color), with or without some black masking on the ears, beard, and tail. Tawnies also can change color drastically over the course of their lives. They are born darker, and gradually go lighter until they are about two years of age. At that point, they begin to darken again, and reach their darkest color at about 4 years of age. An overlay can be very prominent at one age, then virtually disappear. The standard states that the deeper shades of each color are preferred. White is not a correct color, although some Briards, especially at about 2 years, are such a light tawny as to look white.
A black Briard also comes in many shades! True blacks have a glossy, blue-black coat, and they are getting harder to find in the US. True blacks can also come with white hairs intermingled with the black.
Black born grays are born black, but as they age, they develop varying amounts of gray or silver in the coat. The color can range from a slight charcoal appearance, to a silvering of the legs, ears, and beard, to a truly striking silver / black mixture over the entire body. Many blacks today carry the graying gene. When both parents carry this gene, puppies are more apt to be black born grays. They will have black noses, versus blues (see below) that may have lighter colored noses.
Gray born grays, sometimes known as blues, are the least common color. These Briards express the dilute gene in Blacks. They can be identified at birth, by the pewter color of the coat. In the US, the AKC standard calls for a black nose, and blues often come with a lighter nose color, and could be disqualified. In Europe, more of the true grays, the blues born with the color, are seen. As puppies, blues may have less undercoat than blacks. Unlike some other breeds, the blue color in Briards is not linked to any specific health problems.
Why choose one color over another? It's a matter of personal preference, but some broad generalizations can be made. The tawny color appears warmer, more open and friendly. When walking a tawny Briard, even small children want to pet it, often acting as if it is a stuffed animal to hug and kiss. The tawny expression is easier to see, and the variations in color give the dog more visual character. The black, on the other hand, appears more imposing and very elegant. People will stop to say wow!, and ask before petting it. Children recognize that it is a large dog, and are more hesitant to approach. With a black, it mostly the outline that is seen, so a natural eared black can appear to lack expression, unless viewed closely in good light. Remember, it is only the appearance that is different. A tawny may look more open and friendly, but the character of the blacks and tawnies depends on the individual dog, not the color.