This guide is for those of us (including me) who usually don't know what to do with the light colour settings. The colours used here are taken from a Reddit post made by user draeath in the Space Engineers subreddit (link at the bottom).

The settings for your lights can be found under Control Panel. The relevant sliders in there are R, G, B, and will in this post be formatted as R/G/B.

Due to likely similarity with the standard 255 / 255 / 255 setting, not all of the 19 settings from draeath's post are presented, so here are the 14 best...

CANDLE
255 / 147 / 41
40W TUNGSTEN
255 / 197 / 143
100W TUNGSTEN
255 / 214 /170
HALOGEN
255 / 241 / 224
CARBON ARCH
255 / 250 / 244
OVERCAST SKY
201 / 226 / 255
WARM FLUORESCENT
255, 244, 229
STANDARD FLUORESCENT
244 / 255 / 250
COOL WHITE FLUORESCENT
212 / 235 / 255
FULL-SPECTRUM FLUORESCENT
255 / 244 / 242
BLACK LIGHT FLUORESCENT
167 / 0 / 255
MERCURY VAPOR
216 / 247 / 255
SODIUM VAPOR
255 / 209 / 178
HIGH-PRESSURE SODIUM
255 / 183 / 76

The light used in this example was the Inset Wall Light from the Signal DLC. The settings used were:

• Radius — 5
  
• Fallout — 1.3
  
• Intensity — 1

The room in question was just something I hastily put together.

A good tip in general is to size up Radius to fit the room you're in and then crank down Intensity so that it doesn't turn into a flashbang.

https://www.reddit.com/r/spaceengineers/comments/3e0k38/rgb_values_for_various_types_of_realworld_lights/