The traditional scale runs claro, colorado claro, colorado, colorado maduro, maduro, oscuro, with double claro at the pale end. No standards body defines where one stops and the next begins, and makers apply the words inconsistently.
What makes a wrapper dark?
Three things together: how much sun the leaf took while growing, how high on the plant it grew, and above all how long and how hot its fermentation ran. The last of these does most of the work, which is why maduro is described as a process outcome rather than a variety.
Does colour predict strength?
No. Nicotine comes overwhelmingly from the filler, and the wrapper is a single leaf. Dark wrappers tend to read as sweeter and fuller in body, which is a different axis from strength and is routinely mistaken for it.
Shade-grown and sun-grown
Shade-grown leaf is raised under cloth, producing a thinner, paler, more elastic wrapper with fewer veins — Connecticut shade is the best-known example. Sun-grown leaf is thicker and darker and carries more of its own flavour.