Gems Notes and Extracts Augusto Castellani, Mrs. John Brogden 1871

SHELLS. 59it should be resumed, in order that Italy may not losean industry which belongs to her, and from which shemay derive profit.XXY.SHELLS.SHELLS must be permitted to enter in a small degreeinto this treatise, as some of them are used in makingjewels and ornaments.Such are those known by the name of cama, cassisrufa, and cyprea, which are upright, thick, and generallycomposed of strata of varied colours and differentdegrees of hardness. Each of these is composed ofmany very thin lamina, which are perpendicular to thelevel of the principal stratum, which is the hardest,and perfectly resembles enamel ; every lamen consistsof a series of prismatic, lengthened cells, adhering bytheir longest side.It can easily be perceived, from this short description,that some shells can have parallel strata ofdifferent colours distinctly separated, and that, therefore,at a cheaper rate, they can take the place of theonyx and agate used by cameo workers. In fact, theymake very delicate camei of them, because cut with asteel graving tool.It is to be regretted that the art of carving shellcamei, which was, itmay be said, peculiar to Rome,should be now so little valued. This must be caused