heir light refraction; rpt. in AGS. The American Gem Society (AGS) was the first national organization to develop and use a system for determining how well a diamond is cut based against the ideal proportions. The cut grade system uses a scale ranging from zero, being ideal, to ten, being poor. (AGS) ColorDiamonds were formed 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 FG H I JK L MN O P Q R S T U V W X Y Z _AGS -0 .5 1.0 Colorless1.5 2.0 2.5 3.0Near Colorless3.5 4.0 4.5Faint Yellow5.0 5.5 6.0 6.5 7.0 Very Light Yellow7.5 8.0 8.5 9.0 9.5 10Light YellowFancy Yellow Fig. 4. The AGS and the GIA color grading scales with samples; rpt. in GIA. ClarityDiamonds, 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 abse...
