How white light LEDs reflect the colors and how to choose LED to a particular function?

The general color rendering index or CRI, as a measurement of the quality of white color light, from the viewpoint of the reliability of color rendering of the things which are in its new environment started to be used before LED has appeared. Overall color rendering index Ra is perfect, widely used measurement describing the quality of white light. General color rendering index Ra for the solar light, as well as bulbs amounts for 100, however for fluorescent lamps lighting from 50 to 99. The light source with the best color rendering index may amount for 100. Nowadays LED produce white light with the overall color rendering index of 70 to 90. However this index does not characterize all parameters of color rendering of LED, because in case of several LEDs which have the overall color rendering index Ra accounting for 80 detailed index R9(red color rendering) for this diode accepts negative values. That is why it is important that the light emitted by one LED would be as for such index R9 is bigger than 0. Technical data prepared by the manufacturer may include data related to Ra value and delaited indicator Ri=9. Willing to change the drawback of LED determination except Ra and R9 in NIST (USA) new scale of colors projection CQS or Color Quality Scale, reflects the parameters of color projection better than Ra.