An improved assembly for illuminating knobs on an appliance is provided. Light from a light source is positioned below a surface of the appliance to shine through a light transmissive insert in an aperture in the surface to illuminate a bottom surface of a control knob and/or part of the surface of the appliance. A fluid seal is maintained by the assembly between one side of the appliance surface where the knob is positioned, and an opposing side of the appliance surface where the light source is positioned.