Sunday, January 16, 2011

Rare Jade

The most expensive and rarest quality is the uniformly colored translucent green, which, when free from flaws, almost compares with the emerald for beauty. By the Chinese, who are experts in classifying jade, this green color is compared to the vivid green in a peacock's tail. All shades of green are found, however, from the apple green to the emerald green, from the greenish white to the almost white. The poorer qualities, resembling mutton fat in appearance, are of little value and attraction, and although the luster of all jades may be classed as greasy, the medium and poor qualities do not take such a high polish as the best jadeite. Un­equal color, black marks and patches, and white patches are all faults which detract from the value of a specimen. There is not much demand for the "fancy colored" jades. Orange, red, and yellow are amongst the cheaper grades, the lighter greens with green spots or mottled markings, pea greens, and sage greens are all of a moderate value, while the grays and whites are uninteresting and worth very little. The mauves and violets, generally pale, are attractive and are moderately costly, but none approaches the deep, translucent green in beauty, rarity, and value. Fifty-six thousand dollars (£20,000) has been paid in the United States for a string of jade containing only 125 plain round beads. This necklace was 30 inches long and weighed 304 carats, the center bead being only half an inch in diameter. And this necklace had no carved work on it, nor was it of any antiquity. At an auction sale in London during November, 1935, an oval jade bowl of a fine, emerald green color, 7 1/2 inches long by 5 1/4 inches high, was sold for $3,360 (£1200). Jadeite, therefore, might well be regarded as "precious," for it possesses all the necessary qualities of rarity, beauty, and durability, apart from high com­mercial value. The hardness of jadeite is deceiving. Although only 6 1/2 to 7 on the scale of hardness, its structure is of a compact, fibrous nature which renders it exceedingly tough. This toughness, which is one of its remarkable qualities, makes cutting and carving ex­ceedingly difficult, and practically no work on jade is carried on by Western lapidaries. The experience gained over a number of centuries has made the Chinese experts in jade. When mined, large pieces are difficult to break, and since they must be trans­ported, cleavage is effected by applying heat and then suddenly cooling by immersion in water. A pressure of about 50 tons is required to crush one cubic inch of this material. The fracture of jadeite is splintery, but except in thin pieces, it is not easily broken. The peculiar structure may be the reason for the good polish which may be obtained, despite the greasy luster which is so obvious in all the cheaper grades. Specific gravity is 3.44, and refraction is double, giving the constants 1.66 -1.68. Although a hard, tough, and compact stone, jadeite fuses before the blow-pipe and colors the flame a bright yellow. If suitably cut, some jades possess the property of emitting a very clear musical tone when struck, and the vibrations continue for some time. This property, which the Chinese appreciate very keenly, has led to the stone being used in the capacity of sounding plates and tubes. But pieces used in jewelry are either plain cabochon cut, or carved, all shapes being seen. Faceted forms are never used.