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This is a logical question. We have great respect for both organizations, and recognize the GIA's global reach, but prefer the AGSL to grade our diamonds. You may feel better about the choice to use AGSL too, after familiarizing yourself with the below.
Since 1934 the American Gem Society has served as a consumer protection organization. In fact, consumer demand for cut-quality assessment is what fueled the Society's decision to launch their AGS Laboratories in 1996. The AGSL duplicated GIA's color and clarity approaches while adding a cut-quality component (GIA had none at the time). By stepping into this needed space, AGSL quickly became the industry's preeminent authority on cut-quality.
AGSL currently has the world's only scientifically published, repeatable and diamond-specific system for grading diamond light performance. In 2006 the GIA followed by introducing a cut-grading system based on sampled observations, but it's critically wide and lacks the strictness or sophistication of AGSL's scientific system.
AGS takes the same approach as GIA. In fact, AGSL master color stones have been graded by GIA to ensure uniformity between the two labs. When it comes to clarity the approach, nomenclature and standards are also the same. However these are subjective human judgments, which inevitably affect consistency.
GIA grades most of the world's output. Every jeweler in the world has access to GIA graded diamonds. By comparison, AGSL grades only about 2% of diamonds which meet higher standards for cut quality. Some jewelers choose to downplay AGSL to their customers, even though it's common knowledge that AGSL graded diamonds trade for a slight premium over those with GIA reports.
AGSL enjoys absolute consistency in their single lab location. By comparison, the GIA grades over 100,000 diamonds per week across nine locations. Even presuming 90% consistency across all graders and locations; over 40,000 diamonds with some level of grading inconsistencies are flowing into supply lines and website listings every month, which explains the chaos in pricing trends. See our page on Diamond value and pricing for further information.
Relative to each other: There have been and always will be cases where diamonds submitted to both labs are graded differently. The differences go in both directions. Neither GIA nor AGSL are consistently more or less strict on either color or clarity than the other.
GIA and AGS support each other as sister organizations. GIA is the primary sponsor of the annual AGS Conclave, and vice-versa. Industry professionals widely view GIA as the global authority, but consider AGSL the undisputed authority in matters of cut grading.
Since its inception the AGSL has remained focused on consistency, with a single laboratory location, senior graders, peerless research and the world’s only scientifically vetted cut grading system. Their leadership is celebrated and has remained intact for decades with no strife or scandal. Most importantly, they share our strong focus on consumer protection.
All things considered, we believe the AGS Laboratories perfectly reflects the pure diamond research, education and grading body Mr. Shipley had in-mind when he founded both the GIA and AGS nearly a century ago.Back