Abstract: To permit use of a metal halide discharge lamp for general service illumiion requiring a color temperature of below 4100 K., and preferably about 4000 K., or even less, for example about 3500 K., a metal halide discharge lamp is fitted into a reflector and closely surrounded by a closed transparent tube of hard glass or quartz glass, which may be coated with an indium-tin-oxide (ITO) layer. The surrounding tube is retained against the base structure of the lamp adjacent the reflector apex, or fitted against the reflector, and closed at the other end either by an end cap integral with the tube, or by a separate cap element, retrained in position by a bridging strip spanning the light exit opening of the reflector. Preferably, the reflector is faceted.