Chrysoprase is generally cut into a convex form, or what jewellers call en cabochon; and is set with green taffeta beneath it, as foil. It is used for ring stones, brooches, and other ornaments; and is found to harmonize well with diamonds and pearls. The larger and more impure masses are cut into snuff-boxes, seal stones, and similar articles. Some of the finest specimens of chrysoprase that are known, are to be seen in the cathedral church of Prague, where a small closet is inlaid with them.
Imitations of chrysoprase are sometimes imposed upon the public; but these are easily known by persons who are acquainted with the nature of precious stones.
95. BLOODSTONE, or HELIOTROPE, is an opaque stone of the quartz family, generally of dark green colour, with a somewhat bluish cast, and marked with blood-red spots or stripes.
It usually occurs in masses of irregular form; and, when cut thin, is sometimes translucent at the edges.
The most valuable kinds of bloodstone are imported from the East. They are not so opaque as those which are found in Germany, and are marked with more vivid spots. As bloodstone is capable of a high polish, and is even better calculated for engraving upon than carnelian ([93]), it is in great request for seal stones, for the tops and bottoms of snuff-boxes, and other articles on which costly gold mountings are frequently bestowed. Its dark colour and opaque appearance prevent its being much used for beads. Great quantities of it are consumed in China as ornaments to the girdle clasps of the superior ranks of people. Absurd as it may appear, many persons entertain a notion that this stone worn in the dress will prevent bleeding at the nose. Good bloodstone and carnelian are considered to be about the same value.
There are many cameos and intaglios, both by ancients and moderns, executed in bloodstone. In the National Library at Paris, there is a fine engraved stone of this kind, representing the head of Christ whilst undergoing the punishment of scourging, and so cut that the red spots are made to represent drops of blood.
The ancients procured bloodstones chiefly from Ethiopia; but, at present, the most highly esteemed varieties are brought from Bucharia, Great Tartary, and Siberia. A kind of mineral nearly resembling this is found in Rum, one of the western isles of Scotland.
The spots in bloodstone are particles of red jasper.
96. JASPER is a species of quartz, and one of the hardest stones with which we are acquainted. It varies much in colour, being red, green, yellow, blue, olive, violet, black, and often variegated, spotted, or veined with several other colours. It is usually opaque, but is capable of receiving a beautiful polish.
This stone is found in large and shapeless masses, and constitutes an ingredient in mountains of various parts of the world.