Alexandrite is a rare gemstone known for its unique color-changing properties. It appears green in daylight and shifts to a reddish-purple hue under incandescent light. This phenomenon is due to the way the stone absorbs and reflects light, making it highly sought after in the jewelry market. Discovered in the Ural Mountains of Russia in the 1830s, alexandrite is named after Tsar Alexander II. The gemstone is a variety of the mineral chrysoberyl and is valued for its beauty and rarity. High-quality alexandrite can be quite expensive, often fetching prices comparable to diamonds.