.. rmed under intense heat and pressure, and traces of other elements may have been incorporated into their atomic structure accounting for the variances in their color. (Schumann) Diamonds generally range from a shade of yellow or brown to colorless. There are diamonds of other colors such as pink, red, green, blue, orange, and black. These exceptions are rare and sometimes induced by treatments. Diamonds are graded by their color, the AGS and the Gemological Institute of America (GIA) developed color-grading scales.
The scales and some sample stones are pictured in figure four. Colorless and fancy yellow diamonds are considered the most valuable. The differences in color grade are subtle, only a trained professional can properly determine the color grade. (GIA) GIA – D E F G H I J K L M N O P Q R S T U V W X Y Z ? AGS -0 .5 1.0 Colorless 1.5 2.0 2.5 3.0 Near Colorless 3.5 4.0 4.5 Faint Yellow 5.0 5.5 6.0 6.5 7.0 Very Light Yellow 7.5 8.0 8.5 9.0 9.5 10 Light Yellow Fancy Yellow Fig. 4. The AGS and the GIA color grading scales with samples; rpt.
in GIA. Clarity Diamonds, more than any other gemstone, have the capability of producing the maximum amount of brilliancy. Clarity is an indication of a diamond’s purity. All diamonds, except the most rare, have tiny traces of minerals, gases, or other elements that were trapped inside during the crystallization process. These inclusions may look like tiny crystals, clouds, or feathers.
A diamond that is free of interior inclusions and exterior blemishes (commonly called flaws) is of the highest quality. The absence of flaws in a diamond allows for no interference with light, creating a fiery gemstone. Less than one percent of all diamonds ever found have had no inclusions and can be called flawless or internally flawless. (GIA) To determine a diamond’s clarity a professional with a trained eye uses a 10x-power binocular microscope. There are two systems for clarity grading developed by the AGS and the GIA; the GIA system is illustrated in figure five.
Fig. 5. The GIA clarity grading scale with samples and explanation; rpt. in GIA. Carat Weight A carat is a unit of measurement used to describe the weight of diamonds.
One carat is divided into 100 points, so that a diamond of 75 points weighs .75 carats. There are five carats to one gram. Size is the most obvious factor in determining the value of a diamond, but two diamonds of equal size can have unequal values depending on their other qualities. Diamonds of high quality can be found in all sizes, although there may be temporary shortages in certain sizes and qualities due to supply, demand, and availability of rough. (Schumann) Treatments and Synthetics Diamonds are exposed to several treatments to enhance their quality. One treatment is laser drilling, commonly used in the clarity enhancement of diamonds. A focused laser beam is used to drill a narrow channel from the surface to dark inclusions, which may then be acid bleached.
Another treatment is artificial irradiation, which has attained some importance due to the coloring effect produced when the stone is bombarded with particles of atomic size. Irradiation produces a green color, which can be further altered to fancy yellow, brown, orange, and rare pink by subsequent heating under controlled conditions. (EGL) One of the most controversial gemstone treatments to appear in the last decade is the filling of surface reaching breaks in faceted diamonds. The filling of diamonds has proven to enhance diamond clarity by two grades. (Kammerling 145) The diamonds are first cleaned, then filled with a molten glass at high temperatures, cooled, and cleaned again to remove glass from the stones’ surfaces. Claims have been made concerning the stability and durability of various products.
It is virtually impossible to determine exactly how many treated stones are in the marketplace. Recent findings by gemologists indicated that the filling material used in at least one of the treatment processes might decompose when exposed to an ultraviolet lamp or ultrasonic cleaning. The GIA has learned that, while ultrasonic cleaning for a brief period may not damage at least some fillings, extended exposure to this process may cause some shattering of, or other damage to, the filler. High temperature torches used in various jewelry repair procedures may also have adverse affects on treated gemstones. Because of industry concerns about disclosure and detection, it has been suggested that all such stones be laser-inscribed with initials to disclose the treatment.
(EGL) Synthetic diamonds are also on the market. Some of the synthetics have the same exact properties as natural diamond. In 1990, scientists at the General Electric Research and Development Center (GERDC) in New York, announced the production of a new isotopically pure carbon-12 synthetic diamond. Carbon, in nature, consists of a mixture of carbon atoms that have different masses called isotopes. Natural diamond has carbon atom isotopes twelve and thirteen, as do the GERDC synthetics. (EGL) Conclusion Two additional C’s should be mentioned. One of the most important for the consumer is the C in cost. The most obvious of the 4C’s is the carat weight or the size of the stone, which is one of the bigger factors in determining value of a diamond.
The combination of all four characteristics is the final determining cost factor. There are many different combinations of size, color, clarity and proportioning that will affect the final value. (DiNola) Finally, there is the last C confidence, confidence in your jeweler. When you are ready to choose your diamond, see a reliable jeweler, one who is trained and will be happy to explain the four C’s to you. He or she will tell you the difference between various qualities of diamonds and how these differences affect the price. Do not expect to find any bargains in diamonds, quality has its price.
An established jeweler prizes his good reputation and will help you choose the best quality diamond. He or she knows you are looking for quality when you are making one of your most important purchases. (DiNola) Environmental Issues.