The color temperature of a light source is measured in degrees Kelvin. Color temperature is based upon the principle that a black body radiator emits light where the color depends on the temperature of the radiator in degrees Kelvin. Light sources with temperatures below about 3000 K appear “warm” [have a more red/orange look] while light sources above 7500 K appear “cold” as they contain more blue.

A typical incandescent light’s color temperature is determined by comparing its color [hue] with a theoretical, heated black-body radiator. The light’s color temperature is the temperature in Kelvin at which the heated black-body radiator matches the color [hue] of the lamp. 6500 K is the D65 European standard for “daylight” thus a lamp with a color temperature of 6500K would be considered a daylight lamp in Europe.
 
The CRI of a lamp is the Color Rendering Index (sometimes called Color Rendition Index). CRI is a method devised by the International Commission on Illumination (CIE) to measure the ability of a light source to reproduce the colors of various objects being lit by the Light. The best possible rendering of colors is specified by a CRI of one hundred, while the worst possible color rendering would be specified by a CRI of 0.

The higher the CRI of a lamp, the higher the “quality” of the light produced and thus the better the reproduction of colors under that lamp.

TRI R Lighting lamps have a CRI of 80 or more depending on the model and color temperature.