A color rendering index is a scale that measures how well a light source, or lamp, can show the true color of objects. The index is on a scale of 0 to 100, 100 being the equivalent of an objects color under natural sunlight. Typically, incandescent, good light emitting diode (LED), and halogen lamps provide a more natural lighting source and higher CRI's. Poor quality LED, pressurized sodium, and some fluorescent lamps create unnatural colors resulting in CRI's of 60 and below.
Most lamps sold today have a lighting facts area printed on their boxes that rate a lamps color accuracy.