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Ensuring peace of mind when purchasing a significant item like a diamond involves obtaining a diamond grading report or certificate. These third-party validations are crucial, but not all certificates are equal.
Diamond Certification
U.S. diamond certificates generally originate from the Gemological Institute of America (GIA), the American Gem Society (AGS), or the European Gemological Laboratory – USA (EGL or EGL USA).
- The GIA is the foremost and most trusted gemological lab globally.
- The AGS is a reputable non-profit U.S. diamond lab with international offices in several countries.
- The European Gemological Laboratory – USA (EGL or EGL USA).
Differences in Diamond Certification
While the GIA leads the industry, the AGS is a close follower. AGS certifications are preferred over EGL due to differing grading standards. The GIA and AGS, being non-profits, are often trusted more by consumers.
Different labs use distinct grading scales and methods which affect diamond grades and values.
Understanding AGS Diamond Scales
Diamond Color Scale
The numerical AGS diamond color scale begins with 0 (equivalent to GIA/EGL grade D) and progresses in increments. This scale simplifies grading and understanding diamond quality.
Diamond Clarity Scale
Clarity grading varies among labs. The GIA’s scale is widely accepted, but the EGL introduced an SI3 grade causing confusion. AGS clarity uses a straightforward numerical scale for ease of comparison.
Diamond Cut Scale
AGS employs a unique numerical cut scale, simplifying the understanding of diamond cuts. Researching the grading system of the certifying lab is crucial when buying diamonds.
The Diamond Grading Process
The grading process involves using master diamonds for comparison. These diamonds serve as a reference to ensure accurate grading of other diamonds based on color, clarity, and cut.
Discovering the nuances of each certifying lab’s grading system is essential for informed diamond purchasing.
Comparison can only be made in terms of depth of a yellow-looking color.
The grading process requires the use of ultraviolet-free daylight or its equivalent, ensuring no color reflection from the diamond being graded or the master stone. Both diamonds need to be examined against each other from the master set on a full white background, with the viewing direction perpendicular to the pavilion facets or girdle. Minor color variations can be detected under magnification, allowing scrutiny of small areas on both stones to ensure a comparison based on body color rather than reflected color.
Impact of Color on AGS Grading Process
To guarantee that consumers receive genuine and high-quality diamonds, the American Gem Society (AGS) was established. Founded in 1934 by a group of leading jewelers, the AGS aims to protect consumers from deceptive diamond advertising and fraud. Their expertise in identifying fake or flawed gems has saved many unsuspecting consumers from exploitation due to their lack of knowledge in gem purchasing.
When purchasing an AGS diamond, don’t just focus on its sparkle; request the AGS diamond grading report from the organization. This report provides consumers with insights into the factors that determine a diamond’s value. The AGS certification board uses standardized criteria to evaluate diamonds based on color, cut, and clarity on a scale of 0 to 10, with 0 being the highest grade and 10 the lowest. These factors, along with carat weight, contribute to the overall AGS grade.
Color plays a crucial role in the AGS certification process, determining a diamond’s grade on the scale and subsequently influencing its price.
If a diamond receives a color grade of 4, it contains less color compared to one graded, for example, a 6. Lower color grades indicate rarer diamonds that command higher prices. The AGS grading process prioritizes cut, followed by color, clarity, and carat weight. A diamond with the finest cut grade, colorless quality, no flaws, and weighing one carat would be denoted as (0/0/0-1.000) carats.
Grading Fancy Shaped Diamonds
Assessing fancy shaped diamonds differs between AGS and GIA (Gemological Institute of America), as the latter grades them solely by comparing to master diamond sets due to colorimeter limitations. The grading of color and clarity in fancy cut diamonds follows similar protocols as traditional cuts, with angles of observation optimized for balance between minimum and maximum lengths.
The 45-degree grading angle offers more accurate color readings on fancy shaped diamonds, where color accumulation varies based on facet proportions like height, thickness, or crown structure. Facet arrangement significantly influences color grades, and fancy shaped diamonds may exhibit color zoning.
Impact of Fluorescence on AGS Grading Process
Assessing fluorescence in diamonds is a significant aspect of the color grading process for certified diamonds. AGS notes that a small proportion of diamonds, approximately 35%, exhibit fluorescence, resulting in varied color reflections under ultraviolet light. While fluorescence primarily serves as a diamond characteristic identifier, it can affect the diamond’s appearance in certain conditions. Diamonds are examined in a face-up position using fluorescent master stones to gauge fluorescence intensity at different angles, influencing its visibility based on viewing angles.
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