For this post, we will convert this color image of Tiffany to black and white using Nik's Silver Efex Pro 2 plugin. Here is the starting image:
Tiffany in full color.
I converted the color layer (with no layer mask) into a Smart Object (Filter -> Convert for Smart Filter), and brought it into Silver Efex Pro 2. I first chose the 015 Full Dynamic (harsh) preset. To tone down the harshness a bit I adjusted the Structure slider, found in the Global Adjustments section, to -7. Next I chose Green under the Color Filter section. Finally, in the Film Types - Sensitivity section, I fined tuned the Red (-14) and Yellow (-19) sliders, and the result was this:
Final.