Sometimes, looking at a stone at different angles of illumination, you can see how it takes on different shades. This effect is especially observed in some types of stones that contain certain minerals.
There are stones that can change their color depending on the type and intensity of light. They are also called stones with a color change effect. This property of stones is called reverse and is evaluated as a percentage.
What stones change color?
For example, Sri Lankan sapphire becomes dark purple when exposed to electric light. This is due to its high chromium content. Opals are also famous for this quality. These stones, with their incredible color saturation, have given rise to many superstitions.
And if you remember the ability of stones to lose their luster, change color when the temperature rises or when it gets dirty, then you can easily understand the horror and mystical delight that gripped our ancestors. Prone to discoloration of aquamarine, although it cannot compete with opals in reverse performance.
Alexandrite is the most colorful stone
Despite the fact that this property is not so unique, there is a stone that the vast majority of people associate by default with the ability to change its color. This is alexandrite - the stone with the highest reverse.
Alexandrite is the most prized variety of chrysoberyl, one of the hardest minerals. The unusual ability to change color, known as the alexandrite effect, has yet to be fully explained. In daylight, this stone takes on a gray-green or even a very rich green color, which is caused by the high level of chromium, which is not the same in the minerals mined from different deposits.
Green color sometimes has a faint shade of red, this happens depending on the angle at which the light falls on the stone. However, this stone, placed under artificial light, especially from a fluorescent lamp, turns completely red. Sometimes the color transformation can be seen when it is rotated.
Why does alexandrite change color?
There is an old saying: "alexandrite has a red evening and a green morning." Alexandrite, dyed with iron and chromium, absorbs rays of green and red colors especially diligently. Being saturated with sunlight, alexandrite turns into a green stone, and pulling out red rays from the light of the setting sun, it acquires the color of fire, thereby enhancing the different shades of evening and daylight.
The uniqueness of alexandrite is also in the fact that it is the only breed, on the cost of which the reverse effect is positively reflected. Actually, it is appreciated precisely for this ability, while for the same opals, the mentioned effect is considered a disadvantage.
