In diamonds, white light easily passes through the stone and emerges in rainbow colors. The color of a diamond is evaluated by experts under specific lighting conditions and is classified on a scale from D (colorless) to Z (lightly tinted). 

Diamonds labeled D to G are considered colorless and are the most valuable in terms of color grading, followed by those categorized from H to J, which are considered nearly colorless. The colors from K to Z are visibly more yellow and are not as valuable as colorless stones. 

An exception is made for Fancy diamonds, which are extremely rare. They have a vivid, intense color, with the most popular being pink, deep yellow, or light blue. Out of approximately 10,000 carats of polished diamonds, only around 1 carat consists of Fancy diamonds. This rarity often results in these unique stones being traded at multiples of the price of a normal colorless diamond. 

Fancy diamonds are exceptional natural phenomena. Unlike the widely known colorless diamonds with their subtle color gradations within the D to Z color scale, Fancy diamonds are stones whose color is caused by specific light absorption resulting from structural defects in the atomic lattice.