I would almost expect there to have been selenium toning to achieve the color of the darker tones. This is usually done after sulfide toning. Some papers react more readily to the split toning than others. Most warmtone papers react very vividly.
Make a print that is about 1/4 stop overexposed, wash.
Bleach back until some of the highlights are paper white again, wash.
Re-develop in sulfide toner until you find the highlights to have color of your liking. Wash.
Use selenium toner to give the shadows more weight and oomph. This will likely warm your shadows up also, and possibly turn them a bit brown rather than pitch black. Wash.
The results can be staggering. Each washing step is important - chemicals from previous step must be washed out before you put them in the next bath.
I should also add that it looks as though they have added diffusion to this print. The picture is very small, but it looks very soft from what I can tell. Some diffusing material in front of the enlarging lens will do it. I use something as simple as parchment paper, and it works really well. Use it for a portion of the total exposure time for varying effect. Since the material is a tad bit opaque, your total exposure time will be slightly longer.
- Thomas