On the commercial leaf market, cigar wrappers and cigar binders are usually categorized using their color (claro, colorado, maduro, oscuro). High quality leaf (not artificially colored) is lighter in color at the bottom of the stalk, darker as you go up the stalk, and darkest at the very top of the stalk. This same sequence, from the bottom of the stalk to the very top is named volado, seco, viso, ligero and corona for commercial filler leaf. It's just a quirk of the industry, with a lot of leeway. Even more confusing is that the naming practices are different for other types of tobacco, such as burley. But the story is always the same. Larger, thinner, lighter color leaves with lower nicotine come from the bottom of the stalk. As you go up the stalk, leaves become gradually smaller, thicker, darker in color, and higher in nicotine.
What you are looking for is dark leaf, which would be labeled "maduro" or "viso" or "ligero"--however you (or the marketeers) wish to name it.
Bob