If you go into petsmart and look at their selection of lights, the packages are very informative. They tell you all sorts of stuff in layman's terms and in technical mumbojumbo. Also, Home Depot has lights that are made for the home with a kind of yellowish hue that made one of my tanks look like a 70's flick, but they also sell grow lights and aquarium lights that look natural. They sell all sorts of lights that are recomended for different things. I can't tell you exactly whast light to buy, but just browse the stores, and the packaging should describe to you what the light is made to look like. Hope that helps. To tell you the truth though, generally, the better they look, the more expensive.
Also, other conditions in the tank can add to a more natural look, including the background, the substrate, and the tent of the water itself.