Helena Rubinstein, a Polish-American businesswoman, once said this inspiring quote.

You might find her cosmetic empire was irrelevant to our built environment.

But bear with me, let me explain it, so you see a pearl of profound scientific wisdom in it. Two essential measurements tell us what our environment might "look" like in lighting design: one is CRI, the other is CCT.

CRI stands for "Color Rendering Index." It is a quantitative assessment that indicates how the light resource can reveal the color of various objects faithfully compared to a natural light setting.

This index ranges from 0-100, with a perfect 100 indicating that colors under the light source appear the same as they would under natural sunlight.

CCT stands for "Correlated Color Temperature. " It is essentially a way to measure how yellow (warm) or blue (cold) tone of the light emitted from a light bulb. It is estimated in degrees of Kelvin that commonly range from 1700K to 6500K. (the lower the number appeared to be warmer)

There are four primary types of light sources:

incandescent lamps
fluorescent lamps
high-intensity discharge (HID) lamps
light-emitting diodes (LED)

Generally speaking, the incandescent, which includes halogen light, has color temperature ranges from 2700K to 3100K. They have the best color rendering effect, with 100 CRI.

In Helena Rubinstein's beauty world, this type of light is often suitable for cosmetic's "try-on" stands (even with a virtual "try-on" app) or jewelry displays.

Here is the CRI and CCT value for the other lamp types for your reference.

Fluorescent (T5): 75-95/CRI; 3000-4100K/ CCT

Compact fluorescent : 82/CRI; 2700-4100K/ CCT

High-Pressure Soldium: 22-70/CRI; 1800-2800K/ CCT

Metal-Halide: 65-85/CRI; 3200-4300K/ CCT

( metal halide and high/low-pressure sodium are part of HID family )