What Is Turkish Zultanite?

Zultanite is a rare color-change variety of diaspore, found only in Turkey's Ilbir Mountains (Bursa Province). It appears olive-green in daylight but shifts to pink, purple, or red under incandescent light due to trace chromium and vanadium. A relatively new gemstone, it's prized in high-end jewelry, serves as January's birthstone, and is also called Ceylonite or Ottomanite. With a hardness suitable for daily wear, only a few thousand carats are mined annually.