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| Bort |
| Industrial grade diamonds. |
| Carat |
| The metric carat, which equals 0.200 gram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more a stone weighs, the more valuable it will be. |
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| Clarity |
| A stone's relative position on a flawless to imperfect scale. Clarity characteristics are classified as inclusions (internal) or blemishes (external). The size, number, position, nature, and color or relief of characteristics determine the clarity grade. Very few diamonds are flawless, that is, show no inclusions or blemishes when examined by a skilled grader under 10X magnification. If other factors are equal, flawless stones are most valuable. |
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| Coated Diamond |
| A diamond colored by a surface coating which masks the true body-color; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle. |
| Color |
| Grading color in the normal range involves deciding how closely a stone's bodycolor approaches colorlessness. Most diamonds have at least a trace of yellow or brown bodycolor. With the exception of some natural fancy colors, such as blue, pink, purple, or red, the colorless grade is the most valuable. |
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| Cut |
| The proportions and finish of a polished diamond (also called make). Cut can also mean shape, as in emerald cut or marquise cut. Proportions are the size and angle relationships between the facets and different parts of the stone. Finish includes polish and details of facet shape and placement. Cut affects both the weight yield from rough and the optical efficiency of the polished stone; the more successful the cutter is in balancing these considerations, the more valuable the stone will be. |
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| CVD Synthetic Diamond |
| Synthetic diamonds produced by the chemical vapor deposition (CVD) process. They are grown at very high temperatures, but very low pressures. This growth technique can produce thin, brown to near colorless synthetic diamond crystals that are suitable for faceting for jewelry purposes. Synthetic diamonds grown by this new method differ in their gemological properties from those grown by the traditional HPHT technique. |
| Hardness |
| Mineral's resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it. |
| Loupe |
| Magnifying glass usually of 10X. |
| Melee |
| Small Diamonds under .20 carat. |
| Mohs Scale |
| The ten-point scale of mineral hardness, keyed arbitrarily to the minerals talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond. |
| Treated Diamond |
| A diamond with a bodycolor induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing). |
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