For a quick and economical cover job, I use permanent marker. Usually only have to deal with black or brown colors, so your forest green sofa may be a bit difficult to match, but there are definitely green permanent markers out there. If the hue is lighter during the first application, after it dries, go back over the spot again with the marker.
Dab the tip of the marker on the area, don't draw the color on. Then use your fingertip to rub the spot, blending the color in with the leather (also smudges the line seen if you draw the color on, instead of dabbing).
This is only a color fix, which helps hide the obvious damage. As for repairing the texture of scratched smooth leather, I myself would like to know how. Perhaps continuous polishing of that area?
Linda H.
July 2006