pound of essence being derived from seven pounds of scales. From eighteen thousand to twenty thousand fish are required to produce the latter amount of scales. The substance is, therefore, costly; and owing to this fact, and the amount of labor and skill required to make the pearls, they bring a considerable price. They can be distinguished from genuine pearls by their greater hardness, and a colder feeling in the hand. The holes in the false pearls, moreover, are comparatively large, and have a blunt edge, while those made in real pearls are small, and have a sharp edge. False pearls are sometimes made by turning pieces of mother-of-pearl into a spherical form; but they are clumsy imitations, and can be at once detected by the difference of luster as a whole, and the variations of luster on different surfaces. A very good imitation of black pearls is made by cutting pieces of hematite into a spherical form. These counterfeit the luster of the black pearl in a remarkable degree; but can be distinguished by their greater weight and hardness. 220