The mineral appears to be an allotropic form of a simple elementary body which Nature offers to us with lavish hand. And when we consider the triumphs of chemistry, the process of transforming this element into the coveted form does not seem to be so very difficult to the casual thinker. But Nature is stubborn in revealing her simple acts. However, we are not without faith in these determined efforts of scientific skill; for we know that art now produces the brother of the diamond, graphite, at will. And we see that at the soda works at Aussig this form of carbon is obtained as a secondary product by the decomposition of cyanogen and its combinations. We do not, however, look forward with much pleasure to the realization of this idea; for success in producing the diamond will annihilate at a single blow an important article of commerce, and rob ornamentation and investment of one of its most desired objects. Art, however, in its researches on this subject, has succeeded in producing a glass which, when cut, approaches very closely the brilliancy and prismatic display of the diamond. The artificial gems made from this glass, which is supposed to have thallium as a base, instead of lead, are really superior examples of art. “Nothing but glass,” is a phrase too often used contemptuously and unjustly; for these imitations are quite as charming as the adamas itself. In the flash of their rainbow hues, they surpass some of the great diamonds, like the Koh-i-noor; and in brilliancy they exceed all other gems. Their refraction reaches 2 on the established scale, while that of the diamond is reckoned at 2.4, and that of the sapphire, 1.79. They lack, however, hardness; and the effect of time dims their lustre. But this defect may yet be remedied; for the ancients made glass quite as hard as quartz. And when we come to examine those wonderful specimens of ancient glass, with their exquisite colorings, exhumed by General Di Cesnola in the Phœnician tombs of Cyprus, who will venture to establish a limit to the art of glass-making? Even within the past few years, a process has been discovered by which the elasticity and hardness of glass have been increased to a remarkable degree; and if the defect of brittleness can be overcome, a new era in glass-making will have been reached. Artificial diamonds are often worn at the present day; and the fair wearer consoles herself with the hope that, when sunnier days come, the artificial will give place to the real. It will not be soon forgotten by the votaries of fashion, that the Duchesse de Berri, arriving in France, received for her bridal ornaments only the imitation, and that she wore them. CHAPTER XIV. VALUE OF THE DIAMOND.