You pose an interesting question. I know that when I did theatrical lighting, we did take into consideration the skin tones of the cast. I don't know if there is one universal color temperature that works. Getting your makeup ready for daytime use, you should be looking at between 4000K (office lighting) and 5000K (daylight). For evening, you'd be looking at lighting in the 2700K (incandescent) to 3000K (halogen) range. Having a mirror where you can dial in the color is the best way to go. The old makeup mirrors that had a variety of filters you could roll in over the light source would be a good idea. When we are specifying vanity lights, we often have two integrated color temperatures of lighting so that our clients can choose between 2700K and 4000K. One company that does this is Dreamscape Lighting.