Seth Coe-Sullivan flicks the switches on two desk lamps, and even from across the conference room, it’s immediately obvious which light the chief technology officer of QD Vision is there to brag about. The light coming from the lamp on the left is a harsh bluish white. The lamp on the right casts a warmer, more yellow glow. Coe-Sullivan holds a hand under each lamp. The hand under the bluish light looks pale and sickly; the other looks darker and healthier. The harsher light lacks wavelengths in the red end of the spectrum, so there’s no light to illuminate the reddish tinge that blood provides to human skin.

QD Vision, based in Watertown, MA, is promoting a new LED-based lamp that it made with Nexxus Lighting of Charlotte, NC. Nexxus makes a lamp designed to screw into standard sockets used in recessed ceiling lighting. It consists of an array of white-light LEDs encircled by fins that remove excess heat. QD Vision adds an optic–a plastic cover with a special coating that snaps into place over the LEDs.