Game-Changer. The color-change Garnet is a very rare, precious gemstone with a wicked sense of humor. Under lamplight, you may swoon for its intense raspberry pink-purple hue. But once outside, it's turned to blue! This property is called pleochroism, and is caused by the chemical makeup of the mineral. Gemologists sometimes call this gemstone an "Alexandrite Garnet" because it behaves a lot like Alexandrite. It's the perfect gemstone for someone who is unpredictable and loves surprises.Gemstone