Color is a translation of the human eye to the light waves, which are reflected from an object back to the eye.
The color grading technique of colorless to tinted yellow and/or brown diamonds is based on the amount (or absence) of the body color seen in the stone. The technique was established mainly for yellow diamonds, which constitute the absolute majority of goods in the market, but can be used for other shades, while disregarding the hue.

Diamonds of different color intensities
Diamonds of different color intensities

There are several color grading systems used in the world diamond market. The most popular grading system is based on Alphabet letters D to Z, which represent ranges of yellow intensities, where D is for colorless down to Z for tinted yellow. This terminology has been adopted by many of the gemological institutes worldwide. GWLAB uses this system as well, albeit with slight changes.

Inspecting a diamond colors
Inspecting a diamond color

The main concept of the GWLAB system to determine a diamond's color is by comparing its intensity to a set of pre-calibrated color master stones that represent the color ranges. The grades are alphabetically ordered beginning from D (colorless) down to N (near colorless). In these higher grades from D to N, each letter represents a specific grade, but in grades that are below N, the general terms Very Light or Light are used.

The Light grade represents the bottom of the colorless to near-colorless diamonds color range. Diamonds which display color intensity deeper than Light are called "Fancy Colored Diamonds."