The remarkable color-shift in alexandrite occurs due to its unique chromium content interacting with light. This precious stone contains chromium ions that selectively absorb wavelengths differently depending on the light source. In daylight, which is rich in green-blue wavelengths, alexandrite appears green; under incandescent light, which contains more red wavelengths, the same stone transforms to raspberry red. This rare phenomenon, called pleochroism, exists in few natural gemstones, making alexandrite particularly valuable for collectors seeking genuine color-change specimens.