The Diamond was by the ancients called Adamant. It is a precious stone, the first in rank, value, hardness, and lustre, of all gems. The goodness of diamonds consists in their water, or colour, lustre, and weight. The most perfect colour is the white. Their defects are veins, flaws, specks, etc. In Europe, the lapidaries examine the goodness of their rough diamonds by daylight. In the Indies it is done by night. Dr. Wall, in the Philosophical Transactions, seems to have found an infallible method of distinguishing diamonds from other stones : a diamond, with an easy slight friction in the dark, with any soft, animal substance, as the finger, woollen, silk, or the like, appears luminous in its whole body; and if you keep rubbing it long, and then expose it to the eye, it will remain so for some time. Diamonds are found in the East Indies, in Golconda, Visiapour, Bengal, and the Island of Borneo. There are four mines, or rather two mines and two rivers. The miners work quite naked, except a thin linen cloth before them ; and they have also inspectors to prevent their concealing the stones; which, however, they frequently find means to do, by swallowing them when they are not observed. Diamonds have also been found in the Brazils, and hence the terms oriental and occidental diamond; the latter is esteemed the least valuable, but the constituent principle of both is the same, they are all pure carbon, and perfectly inflammable, as Newton concluded. (See p. 20.)