Emerald is a precious gemstone and a variety of the mineral beryl, renowned for its vivid green to bluish-green color caused by trace amounts of chromium and sometimes vanadium. It has a hardness of 7.5–8 on the Mohs scale but is often included with natural fractures, making it relatively fragile. Prized for its rich hue and transparency in top-quality specimens, emerald is the traditional birthstone for May and has been treasured since ancient times.