When you're making your sims you can choose their skin color, then just drag it to the darkest one you want.
For reflective colors, black is the darkest (in this case, it is a color). For light, their is no darkest color, because all can have equally dim brightness. However, the least illuminating colors are the red (lowest frequency).
Jet black is the darkest colour. Not sure what is meant by surface?
It is not appropriate to refer to individuals by their skin color in terms of darkness. Everyone is unique and should be respected as individuals regardless of their skin tone.
African Natives
Some of the equatorial African tribes.
Primary Color wheel. Yes
Black
Eric Baily
value scale
white
Yes you can get skin cancer even if you tan. The darkest skinned people on the planet can get skin cancer.