Cigar wrappers can be classified into seven basic colors, although there are dozens of possible shades:
Double claro (also called AMS, American Market Selection, or candela) is a greenish brown (for instance, as in Macanudo jade.) The color is achieved by picking the leaf before it reaches maturity and then drying it rapidly. It is very mild, almost bland, with very little oil. Cigars with this color have traditionally been popular in the United States, but are very much less so today.
Claro is a pale brown, like milky coffee. (For example, Havana brands like H. Upmann, or brands using Connecticut Shade wrappers.) This is the classic mild cigar color. The color is also called natural, as is colorado claro.
Colorado claro is mid-brown and tawny. (For example, brands, such as Dominican Partagas, using Cameroon wrappers, have this shade.)
Colorado is reddish dark brown and aromatic. This color is associated with well-matured cigars.
Colorado maduro is dark brown, medium strength, and rather more aromatic than maduro. Usually giving a rich flavor, the colorado maduro is found in many of the best Honduran cigars.
Maduro is a very dark brown, like black coffee. (For example, the color of full-bodied Havana brands such as Bolivar; cigars made with Mexican wrappers.) A color for seasoned smokers, which is sometimes thought of as the traditional Cuban color.
Oscuro is more or less black, is very strong, but has little bouquet. Wrappers of this color, though once popular, are rarely produced today. These wrappers tend to be from Nicaragua, Brazil, Mexico, or the Connecticut Broadleaf (as opposed to Shade) type.
The darker the color, the sweeter and stronger the flavor is likely to be, and the greater the oil and sugar content of the wrapper. Darker wrappers will normally have spent longer on the tobacco plant or will come from higher altitudes: the extra exposure to sunlight produces both oil (as protection) and sugar (through photosynthesis). They will also have been fermented for longer.
The term EMS or English Market Selection is a broad one, which refers to brown shade cigars that are anything other than double claro (AMS) essentially.