Plato believed that the gems were produced by a sort of vivifying spirit descending from the stars. It is undoubtedly from the influence of the solar forces and the magnetic and electric currents which are constantly playing through the crust of the earth that the gems derive their origin. These phenomena of the earth’s vitality are manifested in their greatest force along certain elliptics, which may be traced over the true gem districts of Asia, Africa, and Brazil, and in marked contrast to adjacent territories. The miners in South Africa, disturbed by the severe whirlwinds and frequent thunder-storms, soon began to imagine that the excessive electric action had something to do with the creation of the gems they sought. Mr. Voysey, Geologist to the India Survey, also observed the very marked telluric action in the diamond formations of India, and moreover that the process of crystallization took place there with wonderful rapidity. So convinced was this keen observer of the present reproduction of gems in the alluvial soil or conglomerate that he commenced to collect the proofs of recrystallization. Unfortunately for science, Mr. Voysey died shortly after he adopted these views. Dr. Buchanan, another traveller who visited many of the mines of India, was impressed with this idea; and he was assured by the miners all over India that the regeneration of diamonds is always going on in the peculiar gravel. In proof of their statements, many men were then engaged in working over the _débris_ that had been examined many years before. An interval of fifteen years was sufficient in their estimation to reproduce new gems, at least to a certain extent. This reproduction, or rather, we will say, assertion of a reproduction, reminds one of the mysterious action of the nitre beds, which yield rich returns after a rest of a few years, and especially those which occur among rocks which are destitute of potash. It is to the learned Abbé Haüy we owe the theory that crystals are made up of an assemblage of minute parts or molecules, each having the same definite form. To the diamond especially this hypothesis may be applied, since it is composed of thin laminæ covering or concealing its primary form. With the aid of the skill of the artisan we can remove these coverings one after the other, until the definite and elementary form of the crystal be revealed. In the time of Louis XIV. it was thought that the size of diamonds might be increased by placing them in certain solutions, as crystals of salt are enlarged by immersing them in solutions of the same substance. But the difficulty then was to find the required liquid; and even at the present day we have not yet succeeded in discovering the composition of the water of crystallization of crystals of quartz or topaz, although Nature has shown the fluid to us in the cavities of certain crystals.