Chameleon diamonds have a unique color changing nature. When exposed to heat or after keeping the gemstone in the dark for at least one day, its color changes from a solid yellow-green to an unstable yellow. When the heat source is removed from the diamond or it is brought into the natural light, the color reverts back to the stable yellowish-green in a matter of minutes. Some diamonds change color from solid yellow to green when exposed to heat, although not when it is kept in the dark. They are usually called reverse chameleon diamonds.
Chameleon diamonds are not the only color changing gemstones, though. You can also observe color changes in an alexandrite diamond ring. To be precise, the gemstone’s color changes to green in daylight and red when exposed to incandescent light. However, it is not the same as the color change in a chameleon diamond.
Pedro II of Brazil had once owned a diamond, which showed yellow brown color in incandescent light but green in daylight. Apart from that, the diamond alluded to that of Tavernier also had a color change similar in nature to that of alexandrite. Specifically, its color changed to light pink in daylight, but light brown when exposed to incandescent light.