jewel that is in fact not a ruby but one of the world's largest polished red magnesia spinels (see ruby spinel). The unfaceted, 361-carat stone is set in the imperial state crown of England. It is inscribed with the names and dates of six of its owners. The earliest is Shāh Jahāngīr, 1612, and the latest is Aḥmad Shāh Durrānī, 1754.