IRC halogen lamps are sources where the central halogen burner has been coated with an infra-red coating (hence IRC). This reflects the infra-red energy back onto the tungsten burner, which means it heats up and becomes more efficient as much of the reflected heat energy is turned into visible light.
One aspect of lamp colour is its colour appearance; whether the light from the lamps looks ‘warm’ or ‘cool’, measured by the correlated colour temperature (CCT). Lamps with a warm appearance having a CCT of 2700 – 3000K are generally considered appropriate in a domestic setting. Lamps of 4000K and above are considered ‘cool’ and are more appropriate for office and some retail applications.
Colour rendering is also important. This is the ability of a light source to show surface colours as they should be, usually in comparison to a tungsten or daylight source. Lamps with poor colour rendering will distort some colours.