What Is the Difference Between GIA & AGSL Reports on Diamonds?
Customers always want to ensure they are selecting the finest diamond for their budget, which is why they turn to a third-party rating agency to evaluate it. Reputable American organizations such as the Gemological Institute of America (GIA) or the American Gem Society Laboratories (AGS Laboratories) objectively judge a diamond's quality and rarity by scoring its four Cs--cut, color, clarity and carat. Although they are evaluating the same criteria, these entities differ slightly in their rating scales. Does this Spark an idea?
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GIA History
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Since 1931, the Gemological Institute of America has provided gemology research, grading, analysis and professional training in jewelry arts and gemology, according to its website. This California-based nonprofit credits itself for inventing the four Cs, the D to Z color scale and the Flawless to I3 clarity scale for diamonds. Its evaluation reports are called either a GIA Diamond Grading Report or a Diamond Dossier.
AGS Laboratories History
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Founded in 1996, the American Gem Society Laboratories focuses on consumer protection and is affiliated with 1,300 retail jewelers in Canada and the United States. The Las Vegas-based organization reports they are the only laboratory that provides a cut grade for round brilliant and fancy diamonds, according to its website. For diamond analysis, it releases the Diamond Quality Report.
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Cut Rating
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A diamond's cut controls its brightness, fire and scintillation. A diamond's cut is considered the most important factor in judging its value, because it controls the jewel's overall appearance, including brilliance, sparkle and light performance. Under the GIA system, a diamond is given either a poor, fair, good, very good or excellent rating, depending on its design, craftsmanship and appearance, according to GIA website. AGS Laboratories judges the cut by light performance, polish and symmetry, then ranks these on a zero to 10 scale. As its website explains, zero means its an ideal cut, whereas an eight to 10 grade indicates the cut will have negative effects on the stone's beauty, durability or size appearance.
Color Grade
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As the GIA explains, colorless diamonds are the most rare and most expensive, as the majority of diamonds are nearly colorless but may contain yellow or brown tints. It judges a diamond's color based on an alphabetical letter system ranging from D to Z. The D rating means the stone is colorless, while Z indicates it is light yellow or brown. If a stone's color is more pronounced than a Z rating, it's called "fancy," which GIA uses a separate color system to grade. AGS Laboratories uses the same criteria, but rather than D to Z, it uses a zero to 10 scale, with zero meaning colorless, 10 meaning tinted and above 10 indicating fancy.
Clarity Rating
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Most diamonds contain birthmarks which are called "inclusions" if they are internal and "blemishes" if they are external. The less birthmarks it contains, the more valuable a diamond, GIS explains. Its 11-point clarity scale ranks stones from F (flawless) to I3 (highly included). The other ratings are: IF (internally flawless), VVS1 or VVS2 (very, very slightly included), VS1 or VS2 (very slightly included), SI1 or SI2 (slightly included) and I1 or I2 (highly included).
Alternatively, the AGS Laboratory ranks clarity on a zero to 10 scale, with zero meaning no inclusions or blemishes and 10 indicating very obvious inclusions to the unaided eye.
Carat Measurement
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One carat is equivalent to 200 milligrams. Diamonds are weighed in metric carats, which is a standard unit of weight that is equivalent to 200 milligrams, according to the Federal Trade Commission. A point is one, one hundredth of a carat, which means a 50-point diamond weighs half a carat. Both GIA and AGS Laboratories weigh their diamonds in carats.
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References
- Photo Credit diamond image by sumos from Fotolia.com diamonds black 1 image by Renato Francia from Fotolia.com scale image by Pontus Edenberg from Fotolia.com
