HI, Yes it will as Nouvatan adapts to the clients natural suntanned skin colouring. It will still even out the skin tone and give it a natural, healthy, suntanned radiance without looking fake. To be honest you have a job making Nouvatan look fake on any skin tone the shades are so accurate & natural looking!
I tend to not recommend the 14/16/20% on the naturally darker skin tones because they can look a tad over tanned. Unless the client insists on the darker solutions of course!
A 10/12% will bring out his/her natural suntanned skin colouring beautifully, creating a perfect fake tan colour.
Its quite easy to think that if someone has a darker skin tone you can automatically put a darker solution on them. Which in a lot of cases you can, but just be a bit careful as it can take them too dark looking.
Hope that helps a bit.