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→Colour
The colour of light falling on an object affects our perception of the colour of the object (a very complex subject in itself). The colour of a light is expressed as the correlated colour temperature (CCT) or the Colour Rendering Index (CRI).
CCT is measured in degrees Kelvin. CRI is measured on a scale of 0-100, where a light source with 100 CRI is best at producing vibrant colour in objects. A higher CRI rating typically denotes a higher quality lamp. A CRI of 84 or better gives very little shift in an object's colour. Incandescents have an index of 95-100; and tri-phosphor fluorescent runs 84-88. Most LEDs [http://www.cnet.com/news/shining-a-light-on-high-cri-led-bulbs/ score in the 80s], but some [https://en.wikipedia.org/wiki/High_CRI_LED_lighting LEDs are available] with 90; and tri-phosphor fluorescent runs 84-88.
The main colour spectrum of a lamp determines how it makes us feel in an interior space. Colour spectrum is related to a lamp’s temperature. Colour temperature can be soft and comfortable for relaxing or sharp and precise for work environments. The higher the temperature, the cooler the colour of the lamp. For example, a colour temperature of 3000K is warm while 4100K is cool. Indoor lighting is typically 2700K Outdoor lighting is 6500K.