воскресенье, 31 мая 2015 г.

Diamond Clarity - A History of the GIA Grading Scale



Those who have bought diamonds, even with a casual basis, whenever during the last few decades will be aware of the very idea of the 4 Cs. These represent the criteria - diamond clarity, color, cut and carat - which are widely used to reach a standard description of any diamond and, by extension, a cost where it must be valued.

Of those criteria, diamond clarity is the least well understood by the public at large and for that reason usually the one most ignored when buying a diamond. This is often a serious oversight, because clarity may be a key factor in the value of a diamond.

Until the midst of the twentieth century there were a number of systems utilized by various firms and organizations for grading diamond clarity. In 1952, the first serious attempt to develop a marketplace standard began. This scale, referred to as the "diamond grading and evaluation appraisal", was designed by Richard T. Liddicoat, Lester Bensen, Joe Phillips, Robert Crowningshield and Bert Krashes. They drew on various descriptive terms found in the diamond trade during the time to establish the diamond clarity scale which may eventually bring a highly effective standardization towards the industry as a whole. Their system was published these year and adopted through the Gemological Institute of America as their standard for defining diamond clarity. While the GIA diamond clarity scale is by no means universal, it is actually accepted as the most generally used standard in the marketplace.

Griffin and Highbury article

Since its adoption in 1953, this diamond clarity scale has been modified twice. In the 1970s, the GIA became mindful of the point that many diamonds were being ruthlessly cut to get rid of surface blemishes, at the expensive of that particular other important "C" criterion - carat. In an effort to put an end to this particular practice, the institute introduced a brand new grade immediately below the top ranking of F, or flawless. This new grade was IF, internally flawless, and revealed that a diamond was free from internal inclusions but may show slight surface blemishes. This prevented such stones being relegated for the lower grades, out of the flawless category, and managed to get unnecessary to cut them as well aggressively.

Another modification to the diamond clarity scale was in the 1990s. Within the original scale, the best number of grades about the scale, was the I category, with all the I standing for "imperfect". The GIA now changed this to mean "included", in order to take away the stigma of the earlier term.

Diamond clarity is caused by several factors. The very first is the actual size of any inclusions, because larger flaws are definitely more visible. Another is the volume of flaws. On the whole, the better flaws, the reduced the grade, although sometimes a stone may have a hazy appearance which can be a result of a lot of very tiny flaws that are not individually discernible. The third property of flaws could be the position in the stone. This really is especially vital for the casual buyer because, with judicious mounting, it may be easy to conceal flaws in many positions inside the setting.

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