The two images below, one of which is in a current competition (but shouldn't affect the voting in any manner) were both shot in color and converted to B&W using Silver Efex Pro. One is toned via a hard ush to the right on the neutral slider and a heavy application of Silver giving it more a sepia look than B&W. Sepia is definitely a monchromatic effect, so that isn't the problem except that I continued back in Photoshop by copying a section of it which I also posted in textures, then adding the artistic effect of Chrome to the image, reinserting in Silver and re-sepia toning, then back to PS and overlayed the copy section and manipulated the layers so that it is now "duo-toned" for all intent and purposes.
Is it now a color image with B&W highlighting, or is it still B&W because it is noting more than a toned combination??? I really should go to bed when I am sleepy instead of catnapping then coming back on with weird thoughts.
And by the by, all you people who like to work in Textures, try setting your camera to a real high ISO in mediocre lighting...it's really a lot of fun.