Judging The Quality of Diamonds
Source: International Gemmological Institute
One of the most important factors in judging the quality and value of a diamond is the cut. If not cut right, a flawless D color diamond might be considered a reject by a diamond dealer. A poor cut can make a diamond look dull, glassy, bulky and too small for its weight. A good cut can increase its brilliance, sparkle, durability and aesthetic appeal.
At www.discountgoldanddiamonds.com we evaluate diamond brilliance both with the naked eye and a 10-power magnifier. Good diamonds display brilliance throughout the stone. They shouldn't have dark or washed-out areas which allow you to see through the bottom of the stone. Fancy cuts such as the pear, marquise, oval or emerald cut may display a dark bow tie in the center when the pavilion facets are not properly angled. The larger and darker the bow tie, the less desirable and valuable is the stone. Presently round diamonds are valued at approx. 20% more than fancy shapes.
Sometimes we get so involved in analyzing the color, clarity and cut of a diamond that we forget to notice if the diamond is brilliant or not. A diamond can be well cut, yet not brilliant. Color, shape, cutting style, polish, inclusions, transparency and the chemical composition of the diamond also affect its brilliance. If, however, a diamond is highly brilliant, one can assume it's well proportioned.
Clarity is the degree to which a stone is free from external marks called blemishes and internal features called inclusions. Together they represent the clarity characteristics or clarity features of the stone. You may be more familiar with terms such as "flaws," "imperfections" or "defects. The more of these characteristics that are observed using a 10X magnification, the less the value of the diamond.
Most professionals use microscopes to judge clarity, they normally examine the stones with a lighting set up called 'darkfield illumination '. This diffused lighting comes up diagonally through the bottom of the gemstone. In this lighting, tiny inclusions and even dust particles will stand out in high relief. As a result, the clarity of the stone appears to have more inclusions as it would under normal conditions.
Most diamonds seem colorless, but if you look closely, you'll notice that they normally have slight tints of yellow, gray or brown. The strength of these tints partially determines the price of the diamond. Normally the less color a diamond has the more it is worth. Colors are rated by letter, the best being D,E, & F, which are classified as colorless. G,H,I,J are near colorless and the rest of the letters show some form of color.
Judging transparency is also a very important aspect in evaluating a diamond's value. Transparency is defined in the GIA Diamond Dictionary as the: "degree to which a material transmits light without appreciable scattering, so that objects beyond are entire visible." In other words, transparency refers to how clear, hazy, cloudy or opaque a material is.
Clarity and transparency are interconnected but they are different. If there's a cloudy spot in a transparent diamond, the cloud is a clarity feature. If the entire diamond is cloudy due to submicroscopic inclusions, then the cloudiness is a matter of transparency. However, this should affect the clarity grade of the diamond. The more transparency your diamond has the more money it is worth.
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- Diamonds are graded to the internationally accepted system for diamond grading based on color and clarity. Weights and measurements are listed.
- The color grade is established by comparison to prescribed set of master diamonds.
- Clarity grade is established by the assessment of external and internal characteristics.
- The carat weight reflects the official weight of a diamond taken on a well calibrated electronic balance.
- Cut is the exact measurements that reflect the maximum amount of brilliance.
- Since light source and background can have a significant impact on a diamond’s appearance, diamond color is graded in a standardized viewing environment against color masters.
- Diamond Clarity is graded under standard viewing conditions with 10x magnification. Characteristics of the diamond is examined and the clarity is graded, Eternally Flawless (F), Very Very Slightly Imperfect (VVS), Very Slightly Imperfect(VS) Slightly Imperfect (SI) and Imperfect (I) are terms used to describe the clarity of diamonds. The imperfections of the diamond are usally natural in nature.
Diamonds are examined by face up appearance to predict the intensity levels of brightness, fire, and scintillation.