Monthly Archives: December 2014

August Stephenson

August Stephenson – Diamond clarity Clarity is a measure of internal defects of a diamond called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. The Gemological Institute of America (GIA) and other organizations have developed systems to grade clarity, which are based on those inclusions which are visible to a trained professional when a diamond is viewed under 10x magnification. Big Hole diamond mining: From 1871 to 1914, 50,000 miners dug the Big Hole with picks and shovels, yielding 2,722 kg of diamonds, The various smaller mining companies were amalgamated by British imperialist Cecil Rhodes and Charles Rudd into De Beers, and The Kimberley under Barney Barnato. In 1888, the two companies merged to form De Beers Consolidated Mines, which once had a monopoly over the world’s diamond market. August Stephenson August Stephenson The price per carat The price per carat does not increase linearly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less. As an example, a 0.99 carat diamond may have a significantly lower price per carat than a comparable 1.01 carat diamond, because of differences in demand. Diamond Gemological characteristics The most familiar usage of diamonds today is as gemstones used for adornment—a usage which dates back into antiquity. The dispersion of white light into spectral colors is the primary gemological characteristic of gem diamonds. In the twentieth century, gemologists have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics known informally as the four Cs are now commonly used as the basic descriptors of diamonds: carat, cut, color, and clarity. August Stephenson responsibility, skills, and professionalism CRYSTAL – For a diamond or colored gemstone, a visible crystalline structure of variable transparency on the interior of the stone. This can occur naturally or as a result of a treatment, and typically serves as an identifying characteristic. On EGL USA reports, it is plotted for diamonds (see also Plotting Diagram) and noted as an identifying characteristic for colored gemstones. INTERNAL LASER DRILL – In a diamond, a flat channel-like feature created by a laser beam during the treatment of an included crystal. The internal laser drill extends from the inclusion to the stone’s surface, where it appears as a linear feature. See also Plotting Diagram. MOHS SCALE – A loose scale of hardness, used for field collecting, which allows for identification of specimens. Devised by Friedrich Mohs, a German mineralogist, in the 19th century. The comparative scale of hardness is as follows: 1) Talc 2) Gypsum 3) Calcite 4) Fluorite 5) Apatite 6) Feldspar 7) Quartz 8) Topaz and Beryl 9) Corundum 10) Diamond MOUNTING – The portion of a piece of jewelry in which a gemstone or other object is set.