I have a Black Isle tank, which I believe is the same tartan as commonly referred to as the Dark Douglas. The tartan pattern is extremely subtle as the only color difference is basically between black and a very slightly lighter shade of black, such that the tartan pattern is really only visible in decent light. I love it as it doubles as a basic black while also being a tartan in the right light. It is NOT the same as the Shadow tartan, however.

Picture in dark light where tartan is practically invisible:





Picture in overcast daylight:





Picture is bright sunlight:




I also have a weathered Macdonald but no pictures. The black is beautiful if you have a taste for it.