Halogen filaments naturally produce a color of 2300K to 4000K (2300K is yellowish, 4000K is whitish) Anything bluer requires the use of light-dimming color filters.
Trying to emulate this color-flickering effect with a solid-state blue or purple bulb is only detrimental to lighting performance, it doesn't fool anyone, but most importantly it endangers other motorists around you. Blue light has what we call a very high diffuse density, which causes it to radiate outwards as opposed to forwards. What results is a wide glow of light outside the beam pattern that is blinding to motorists you share the road with. A blue HID bulb will produce color bleed around the headlight, around the objects it lights up, outside of the beam pattern, and around the cut off line.
...later at night im driving back home grom work and the new lights are on and i can barley c the yellow lines.
Blue light also shifts the color hue of everything on the road to blue scale, which fatigues your eyes more than a standard halogen bulb, and it's brightness isn't that much of a marked improvement over a xenon-filled halogen bulb.
Sylvania (stock basically..)