Carnelian
Posted on June 17, 2008
Filed Under Uncategorized |
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 be called carnelian. The term comes from the Latin caro or carnis, meaning “flesh,” or from corneolus and carnevolus, on account of its resemblance to the color of flesh or to the fruit of the cornil tree.
Faint stripes are often seen within the stone, but if the stripes are very marked, such specimens should be called striped agate, or red agate. The darker brownish-red stones are really sard, so it will be seen that the three varieties grade into one another. Occasionally, ruddy patches mar specimens that are otherwise uniform in color; deeper shades of red are uncommon in nature, most of such marketed stones being the result of artificial treatment.
The natural color may be improved by various means since the material is porous. The rough stone is treated before being cut; it is heated to a certain temperature, according to the nature of the stone, and then treated with ferrous sulphate. There are other methods, but this is the one usually adopted in Idar-Oberstein. Some stones split and are entirely spoiled if care is not exercised; if too much heat is applied, the material crumbles to a white powder. The alteration in color seems to depend upon the amount of iron oxide within the stone, and the process calls for skill and much experience before success may be obtained.
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