WHAT CAUSES THE COLOR CHANGE IN ALEXANDRITES?

Alexandrite is a rare and valuable gemstone that is prized for its unique color-changing properties.

When viewed under different lighting conditions, this gemstone can appear green, blue, or even purple. So, what causes this remarkable color change?

The answer lies in the crystal structure of alexandrite. This gemstone is a variety of the mineral chrysoberyl, and its color-changing properties are due to the presence of trace elements in its crystal lattice. Specifically, the presence of chromium within the crystal structure is responsible for alexandrite’s color-changing properties. In natural light, alexandrite appears green or blue-green, but under incandescent light, it can appear reddish-purple.

This color change is known as “the alexandrite effect“, and it is caused by the way the chromium atoms absorb light. In natural light, the chromium atoms absorb light in the blue and green regions of the spectrum, giving the gemstone a green or blue-green color. However, under incandescent light, the chromium atoms absorb light in the red region of the spectrum, giving the gemstone a reddish-purple color.

Alexandrite is not the only gemstone that exhibits color-changing properties. Other gemstones that exhibit color change include:

1. Sapphire: Some sapphires can exhibit a color change from blue to purple under different lighting conditions. This is due to the presence of trace amounts of vanadium within the crystal structure.
2. Garnet: Color-change garnets can exhibit a color change from blue-green in daylight to purplish-red under incandescent light. This is due to the presence of trace amounts of vanadium and chromium within the crystal structure.
3. Spinel: Color-change spinels can exhibit a color change from blue-gray in daylight to purple-red under incandescent light. This is due to the presence of trace amounts of chromium within the crystal structure.
4. Diaspore: Color-change diaspore can exhibit a color change from greenish-yellow in daylight to reddish-brown under incandescent light. This is due to the presence of manganese within the crystal structure.

In conclusion, the color change in alexandrite, as well as other gemstones such as sapphire, garnet, spinel, and diaspore, is caused by the presence of trace elements within their crystal structure. These gemstones are highly prized for their unique color-changing properties, and they are a testament to the beauty and complexity of the natural world.

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