The Mystique of the Classic Chameleon Diamond.

The pear-shaped chameleon diamond shown above, showcased by Leibish & Co., illustrates this remarkable transformation. Image courtesy of Fancy Diamonds, under the Creative Commons Attribution 2.0 license.

Classic chameleon diamonds undergo a fascinating color transformation. They switch from a stable yellowish-green to yellow. Keep the diamond in darkness for at least 24 hours to witness this color change or heat it between 200-300° C. It then adopts an unstable yellow hue. Once exposed to light or after removing the heat source, the diamond returns to its original yellowish-green color within a few minutes. This phenomenon typifies a "classic" chameleon diamond. Meanwhile, certain diamonds transition from a stable yellow to green upon heating but not when stored in the dark. These variants are often referred to as "reverse" chameleon diamonds.