Diamond Small 320×287 Medium 640×574 Large 1024×919 Download Tiff Original 2400×2154 | (444.9 KB) Description "Pure crystalline carbon, the hardest substance known, possessing great lustre owing to its great refracting power." — Williams, 1889 Keywords carbon, crystalline, cut, diamond, geology Galleries Crystals Source: H. L. Williams The World's Cyclopedia (New York: World Manufacturing Co, 1889) 149