Gemstone Basics cont'd
Classic Crafts
Inclusions are when a gemstone has foreign matter of some sort inside. There is hardly a gemstone which is completely clean. Most of the time there may be some kind of dislocation or irregularity in the crystal lattice. Sometimes you can only see these flaws under a microscope. Inclusions can tell a lot about the origin of the gemstone deposits and help in their identification. Inclusions of minerals are quite common and sometimes there is younger crystal formations starting inside that causes rutile needles inside the stone.
The oldest way of decorating a gemstone is the scratching of figures, symbols, and letters on it. Stone cutting culminates in the faceted stone. In the manufacture of gemstones, one differentiates between engraving, working of agates, colored stone, ball or cylinder cutting, working of diamond, and the piercing of gemstones. Commercially, there is no strict division between these. Cutting and polishing is called lapidary work. The cutter is known as a lapidary. Most lapidaries specialize in a certain gem or stone group, so that consideration can be given to the best characteristics of the stone, such as depth of color, pleochroism, or hardness. Circular saws with edges containing diamond powder instead of teeth are used first to cut the stone roughly to the required size. The final shape is given to the rough stone on a vertical, roughly grained carborundum wheel, cooled with water. Opaque stones, or those with inclusions, are cut cabachon on grooved carborundum wheels. Transparent stones after being roughly shaped, are faceted on horizontal grinding wheels. The substance of the cutting wheel and the type of polishing powder , wheel speed varies with the stone to be worked on. Gemstones may be pierced to make jewelry. High-speed electrical drills are used and have to be continuously provided with a coolant. Diamond powder and polishing paste help with the drilling procedure. Both sides are usually drilled so that the stone does not splinter at the original hole. Cutting and polishing are done after inspection with a loupe. A loupe is a magnifying glass. Cutting and polishing can take several weeks. Polishing requires much experience. The facets of the diamond are help in a dop and polished on a horizontally running wheel primed with diamond powder and oil, rotating at about 2000 - 3000 rpm. The corners of all facets and angles are judged by experienced cutters eyes using a loupe to gauge the cut. The loss of material can be very large as high as 50 - 60 %.
Well, there you have the basics of gemstones and many terms that are used with them. I hope that this information has helped you understand the wonder world of gemstones!!