Large holes or thicker slabs of material are usually drilled by electrical power, high speed electric drilling machines being used, and these have needles or tubes which are charged with diamond dust and oil. But all small stones, such as beads, earstuds, ring stones, and stones for links are drilled individually and by hand. Moreover, there are certain stones such as jasper, malachite, tiger-eye, and lapis lazuli which vary slightly in hardness owing to their composition. Such materials are always drilled by hand as a machine operated drill would be quickly broken if used. The touch of the cutter and driller is so practised that they can almost always tell the hardness of a stone, and they are able to distinguish its species from its resistance to a drill. A cutter is also able to say in most instances where a stone has been mined. For instance, a diamond cutter can tell from which area a given diamond has originated, and whether it is an alluvial or a mined stone. This is not so easy now that many new fields have been developed. The mined stones from Namaqualand in South Africa are very similar in working to alluvial found stones. The latter are generally considered to be whiter, but they sometimes develop a tinge of color when cut. Chilean lapis can be differentiated from Persian lapis, American turquoise from Persian lapis, and so on.
Many stones are cut in their country of origin, although many of these need recutting when they reach the European or American markets since they often do not satisfy the standards demanded in these western countries. For instance, most of the Ceylon cut stones, such as sapphires, rubies, and garnets are refashioned on their arrival in Europe. Russian cut amethysts from the Urals are generally cut too deeply so that they appear “thick,” and such stones are very difficult to mount in jewelry. Siam cut zircons are often well cut, and jade from China is usually so well designed and finished that no improvement is necessary. Brazil now cuts many of the stones found locally, and an important industry has developed there since 1942. Opals cut in Australia are usually too thick and the shapes are often unusable. All these faults are primarily due to the desire to retain as much weight as possible without proper regard to shape and proportion. We have dealt further with the cutting of certain species when they were described individually in their individual chapters.
