I found a tutorial to colorizing using a gradient in Photoshop. In fact, if you want to do it, you can find the tutorial right here: http://www.photoshopessentials.com/photo-effects/gradient-map/
I followed the instructions, and decided to apply the effect with a Purple to Orange to Green gradient. Sounds a bit like vomit, but I have to say, the final effect turned out nice. It ended up being a bit of a sepia-tone effect. I had chosen a still life shot I made in Barkerville, British Columbia last summer. The school bell is surrounded by some slate tablets and aprons. I stacked the tablets pretty after the kids were finished with them and snapped off some quick shots. I’m most impressed with how the monochrome effect really made the texture stand out.
Here is what I ended up with. Hope you enjoy.