George Frederick Herbert Smith, Gem-Stones and Their Distinctive Characters
“ The colour-dispersion is large, being as much as 0·044, in which respect it surpasses all colourless stones, but is exceeded by sphene and the green garnet from the Urals (cf. p. 217) . The lustre of diamond, when polished, is so characteristic as to be termed adamantine, and is due to the combination of high refraction and extreme hardness. Diamond is translucent to the X (Röntgen) rays; it phosphoresces under the action of radium, and of a high-tension electric current when placed in a vacuum tube, and sometimes even when exposed to strong sunlight. ”
