Light Set-up Cyan; I really love this color, it gives a dark and cold mood that is really nice . The mix with the CTO is perfect to me. For this image I installed a Stripbox at with the cyan, and a square softbox with a CTO filter.
Studio Lighting Tutorial - Awesome Headshot Lighting
These different types of lighting create different gradients and colours of light giving an image more meaning and depth. The way the light is enables the image to be more interesting and direct to what you want for your shoot.