All discharge (HID) BULBS in automotive applications are DOT regulated and contain very similar (if not exact) gas compositions if they are installed OEM. HID lamps contain a mixture of salts that help facilitate the arc of power that produces the light within the bulb. Since they do not have a filament, the salts produce a means to control the burn. Gravity pulls the salts to the bottom of the bulb. If you ever look at an HID bulb you will see a nice yellow spot on the bottom near the electrodes while it is off. As the bulb heats up and the pressure builds, the salts vaporize in the arc. HIDs have to be shielded so that the yellow light (light coming through the salts) does not make it to the road. Again look at your headlamp, a shield is there to block the light coming from the bottom of the bulb--it never reaches the reflector. In general new HID's produce a light in the 4100-4300K range. This is very white and shifted slightly toward the blue range. In a fixed reflector system like the IS300 this is the color that you see and it appears pretty white when you look at it. In systems that use high effeciency projectors, however, the light often looks bluer and can look purple. This is because there is a shield in the reflector that blocks some of the light before it passes through the projector lens. The shields are often razor thin along the top edge. Light is defracted on this sharp edge. If the shield is moved towards the focal plan, then you get an amplification of the blue end of the spectrum. The defraction then gets refracted with the rest of the light at the projectors high-powered lens and you get an image on the road. Only a small portion of the light is in the blue spectrum but it is right at the cut-off of the beam so you see it flash as the cars' headlights come toward you. The main portion of the beam is no different than what our cars produce. For proof, compare any car with a fixed reflector to the IS300 and they will look similar (older LS430, Acura RL). Projectors from different manufacturers will be blue looking in general. It is true that HID's will become bluer with age. There is an explanation for that if anyone cares. The only way to make the IS appear bluer is to change to an aftermarket bulb that promises increased Kelvin Temperature ratings. These bulbs will make the entire beam change colors and won't look like the light you have now OR any of the factory projectors that appear more blue from OUTSIDE the car. They also will produce less overall light. I can explain that too if anyone cars. I have a doctoral degree in optics so i'm not making this up.