England once had the monopoly of tortoiseshell, but for some years, other countries have had a large share in the trade. The Indian islands are now probably the chief suppliers, and the em-poria are Singapore, Manila, and Batavia. The shells find their way to Germany, Italy, England, and France, where they are worked into the different articles which may be seen in most cities. Italy produces most of the finished goods to-day.
Some years ago, the piqu£ gold and tortoiseshell ornaments were very fashionable, but owing to decreased demand, they are now not manufactured. At the London International Exhibition of 1851, a Parisian manufacturer showed an exceedingly fine display of tortoiseshell jewelry. In China and Japan, cups are still made from shell, but in England, little else than boxes, cigarette holders, combs, spectacle frames, and the backs of brushes and mirrors are now made, and even those are in small demand.
As with anything of commercial value, tortoiseshell is now widely imitated, and plastics are used in most instances. Translucent horn, stained to the correct color, is also sometimes used to simulate the natural shell. Modern plastics, of which a very large range may now be had, make excellent superficial substitutes for many opaque and translucent materials since they can be made in any color. Their extensive and growing uses are, however, of more importance in spheres outside jewelry. If heated, the casein plastics char and give off an odor similar to that of burning milk; tortoiseshell fuses to a black mass, which smells like burning hair. Further, the microscope will reveal round, reddish particles in tortoiseshell, which are absent in the plastics. The refractive index of tortoiseshell is about 1.55, and the specific gravity 1.26 to 1.35.
Jan 27