All the answers are correct. Tobacco stains can be removed with everything from lemon juice to bleach. The safest and healthiest way to get rid of the stains is let the nails grow out as the new portions will not be stained. If you have stains on your fingers as well (common with cigarette smokers), you can also use an exfolient. The reason that cigar bands were placed on cigars is so that the aristrocrats would not have tobacco stains after smoking a cigar. They would hold the cigar through the band and only smoke it up until they reached the bands. The cigar band was created for women as the queens would smoke cigars and did not want their fingers stained.