White light usually varies from 6500K (brightest blue-white) down to about 2700K for CFL “warm white”. You can get yellower/redder if you take an incandescent bulb and dim it. For color grading, the standard is somewhere between 6500K and 5500K, close to the color of noon northern daylight in South Africa, which is where color grading started with diamonds. You will just have to look to find a penlight whose color temperature is specified. There are LEDs with about 5500K and some that have warmer light.
As far as UV is concerned, you will find those lights fairly dim compared to the white lights. There is no particular “required brightness.” You just use a UV light to see if your stone fluoresces and that is observed in a dark environment, so the light does not have to be real bright. The stone glows brightly or dimly and that is what you take note of…the color of the glow and its intensity, too. Both LW and SW are useful for gem ID, Make sure not to look directly at the SW UV light, it can damage your retina. You can get UV lights specifically for gem ID, like the Raytech Versalume, but these days there are lots of LW penlights and some sanitizing UV lights that will work for SW, too.