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Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. However, large clouds can affect a diamond's ability to transmit and scatter light. Large cracks close to or breaking the surface may reduce a diamond's resistance to fracture. Diamonds with higher clarity grades are more valued, with the exceedingly rare "flawless" graded diamond fetching the highest price. However, minor inclusions or blemishes are sometimes considered to have some value, as they can be used as unique identifying marks analogous to Fingerprint s. In addition, as Synthetic Diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin.. INCLUSIONS AND BLEMISHES There are several types of inclusions and blemishes, which affect a diamond's clarity to varying degrees. Features resulting from Diamond Enhancement procedures, such as ''laser lines'', are also considered inclusions and/or blemishes.. Inclusions
Blemishes
CLARITY GRADING The Gemological Institute Of America (GIA), as well as other diamond grading agencies including the European Gemological Laboratory (EGL), American Gemological Society (AGS), and the International Gemological Laboratory (IGL) use a sliding grading scale based on descriptive terms of overall clarity. These grading agencies base their clarity grades on the characteristics of inclusions visible to a trained professional when a diamond is viewed from above under 10x Magnification . The diamond clarity grades in common use are:
All grades reflect the appearance to an experienced grader when viewed from above at 10x magnification, though higher magnifications and viewing from other angles are used during the grading process. In "colorless" diamonds, dark inclusions will tend to create the greatest drop of clarity grade. In other colors pale inclusions may have greater relief (may stand out more) and may cause a greater drop in grade. Beyond the clarity grading terms, other considerations include the type, size and location of the "inclusion". Inclusions near or on the surface may weaken the diamond structurally. Depending on where the inclusion occurs in the cut diamond and how it is to be used, it may be possible to hide the inclusion behind the setting. RARITY AND VALUE Diamonds become increasingly rare when considering higher clarity gradings. Only about 20 percent of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80 percent are relegated to industrial use. Of that top 20 percent, a significant portion contains an inclusion or inclusions that are visible to the naked eye upon close inspection. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers, although visible inclusions can sometimes be hidden under the setting in a piece of jewelry. The most popular gem diamonds fall within the VS and SI grades with F, IF, and even VVS stones commanding significant premiums, while I stones are shunned by most buyers. F and IF stones are sometimes referred to as "museum quality" or "investment grade" to denote their rarity, although the term "investment grade" is misleading as diamonds have historically been Illiquid and questionable stores of value. CLARITY ENHANCEMENT ''Main article: Diamond Enhancement '' Laser "drilling" involves using a laser to burn a hole to a colored inclusion, followed by acid washing to remove the coloring agent. The clarity grade is the grade after the treatment. The treatment is considered permanent and both the GIA and AGS will issue grades for laser drilled diamonds. Reputable vendors should disclose that laser drilling has been used. Clarity can also be "enhanced" by filling the fracture much like a car windshield crack can be treated. Such diamonds are sometimes called " Fracture Filled Diamonds ". Reputable vendors must disclose this filling and reputable filling companies use filling agents which show a flash of color, commonly orange or pink, when viewed closely. There is a significant price discount for fracture-filled diamonds. The GIA will not grade fracture-filled diamonds, in part because the treatment isn't as permanent as the diamond itself. Reputable companies often provide for repeat treatments if heat causes damage to the filling. The heat required to cause damage is that of a Blowtorch used to work on settings, and it is essential to inform anyone working on a setting if the diamond is fracture-filled, so they can apply cooling agents to the diamond and use greater care while working on it. SEE ALSO |
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