Crystallized quartz absolutely free from any coloring matter is known as rock crystal. In the time of Pliny such limpid, water clear silica was supposed to be simply petrified water, a belief that was only abandoned when the spread of knowledge in the eighteenth century caused this, as well as many other mineralogical myths, to be decried.
In relation to present day jewelry uses, rock crystal may be said to supply material for necklace beads, either as facetted beads or as the small flat separators used between beads of other materials which are known as rondels.
Rock crystal is preeminently a medium in which carved art objects are wrought. Since the supply of material for these is limited only by the size of flawless quartz crystals obtainable, it is obvious that the value of such pieces depends on their size, and especially on the amount and quality of work involved in the fashioning of them.
To the layman the best known of these rock crystal carvings are the highly polished spheres produced in all sizes up to a foot in diameter by the Japanese lapidaries.
Such rock crystal balls are now, no doubt, being made by methods involving some variation of the turning lathe introduced into Japan from Europe or America. As recently, however, as the closing decade of the last century, the methods and tools employed in their cutting were of the most primitive sort. The writer is familiar with a set of small rock crystal balls in all stages of completion, which, together with the simple tools employed in their manufacture, were brought back from Japan in the “nineties” by the late Dr. Thomas Egleston.
The tools consisted of a long, narrow piece of steel, shaped somewhat like a carpenter’s gauge, and a joint of the male bamboo, both of these being of a size commensurate with the diameter of the ball to be cut. A quartz fragment of appropriate rough shape was rubbed against the concave steel edge until the rough corners were chipped and worn off, and the piece assumed a rough spherical shape.
The smaller irregularities were then reduced by rubbing with the bamboo joints, into the pores of which quartz dust had worked its way and so acted as an abrasive.
Polishing was done with a fresh piece of bamboo, either charged with rouge or uncharged with any abrasive. Months of arduous labor must have gone to the making of one of these rock crystal spheres as fashioned in this way; and since a flawless rock crystal of greater diameter through the prism than the diameter of the resulting ball is required, it follows that the value of them increases very rapidly with an increase in diameter.
A rock crystal ball four inches in diameter is worth a great deal more than twice the value of one of two inches in diameter, and probably nearer in the neighborhood of four times this value.
Two very simple tests suffice to detect a glass imitation of a rock crystal ball. In the first place, glass is seldom free from round bubbles, which even when very small are visible with the aid of a hand lens. Also, quartz, although doubly refracting to only a relatively small extent, will still show double images of fine lines viewed through even as small a thickness as an inch and a half.
The double refraction test is easily applied by shifting the ball in question over a sheet of printed matter so that periods or dotted i’s will be seen through different directions. If the material is rock crystal, a position will be found in which two images of the printed type will show through the ball.
In addition to the Japanese rock crystal spheres, clear quartz has been used in China for several centuries as a material for the carving of a great many beautiful and interesting small objects, such as vases, snuff bottles, figurines, ink boxes, incense burners and pendants.
With the exception of the covered boxes of square or polygonal shape, designed to hold india ink, all of the above mentioned objects have also been made from amethyst and rose quartz, and sometimes also from smoky quartz. Frequently an area of amethyst inclosed in a mass of rock crystal is adapted in the carving to represent some feature of the design with great taste and skill.
In sharp contrast to the freedom and native grace that mark the Chinese carvings in rock crystal are the laboriously elaborate carved objects in this medium that were produced in the Imperial Lapidary Works at Ekaterinburg, Russia, during the nineteenth century.
These include such Victorian ornaments as formal “coupes,” seals, paper weights, flat dishes, as well as occasional figurines, cane and umbrella handles and such trifles. These were all executed with an elaborate formality that gave to them an almost architectural aspect in keeping with the period that produced them. Their very elaborateness, however, was emphasized by a rare skill in execution and a considerable taste in the combining of matte and polished surfaces in the working out of the designs.
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