Chrysoprase
Natural chrysoprase is of a fine apple-green color, somewhat resembling certain jades and amazonites. Duller, and of a different texture from jade, and without the tinge of blue and the pearly sheen which distinguishes amazonite, chrysoprase is seldom a deep green, imperfections being very common. It is often streaked with white, and cracks are quite [...]
Plasma
This is dull, leek-green stone, often speckled with white (but not red) spots. Yellow markings are also sometimes seen. It is opaque to sub-translucent, and except for its markings, it is the same as bloodstone. The dark green color is due to inclusions of green earth (or delessite).
Prase is much the same as plasma, except [...]
Jasper
Jasper is a massive, compact quartz, usually containing many impurities. Opaque, dark red, brown, yellow, green, or gray, the included ferric oxides, iron silicates, and clay give rise to the different colors, which are all rather dull. The internal structure is so fine that the constituents cannot be recognized except by analysis.
Bloodstone
Slightly more interesting than sard, bloodstone is also opaque, although its dark green color is relieved by small red spots. The better material is evenly distributed with these spots; that containing larger marks or stripes is considered to be inferior. Occasionally mounted in rings, sometimes carved, it is worn by some who consider it their [...]
Sard
This is identical with carnelian, except for color, which is a deep brownish-red. The brown is pronounced, and it sometimes approaches black, but it is never attractive and is therefore seldom used in jewelry. Sometimes internal black specks may be seen, and some specimens improve on heating.
It is found, often with carnelian, over a wide [...]
Carnelians Origins
Stones found and cut in India and China are not often treated, and they are therefore generally paler in color than those which emanate from Germany. Indian cut stones are usually irregular in shape; beads are drilled from each end separately and the holes are seldom true. On the other hand, Chinese work is usually [...]
Carnelian
This is the popular translucent brownish-red or flesh red colored chalcedony, often seen in bead necklaces as well as in cabo-chon forms, mounted in rings, brooches, pendants, and earrings. Many stones are pale in color, and in addition to the reddish shades, milky white and yellows are occasionally seen, although these strictly speaking should not [...]
Agate Cutting
Now, cutting is carried out by steel laps, the edge of which is coated with silicon carbide, and although electricity has taken the place of water power, a few agate mills still remain. In these, the large grinding wheels revolve partially submerged in the running water, the rate of revolution being about three times per [...]
Agate Origin
Agate is found in cavities, often irregular in shape, and also in holes in old lavas. It has resulted from the deposits of silica being thrown out of solutions, the shape of the bands following the shape of the cavities. Often, the layers suggest the outline of an almond, many beautiful designs being seen.
Agates are [...]
Agate
This variety is essentially striped, the stripes or bands varying in width and color, according to the conditions present during formation. The stripes may be distinct or faint, but they can generally be seen under a microscope. The differently colored bands may be wide or narrow: a stone examined by Sir David Brewster was found [...]
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