The Gemological Institute of America (GIA) is the leading authority on diamonds, colored stones, and pearls. Its Gem Trade Laboratory (GIA-GTL) plays a crucial role in the diamond and jewelry industry.
The GIA and GTL are separate divisions of a gemological family, including the American Gem Society. Together, they form a circle of gemological education and trust heavily relied upon by consumers and the trade.
What is the GIA Gem Trade Laboratory?
The Gemological Institute of America's Gem Trade Laboratory (GIA-GTL) is a specialized division within the GIA. It provides unbiased, accurate gemstone grading and identification services. This laboratory sets the benchmark for quality and integrity in the gem industry.
The Birth of GIA-GTL
Established in 1931, GIA aimed to bring order and standardization to the global gem trade. The GIA-GTL was founded in 1953 to offer reliable gemstone evaluations. It upholds these values today, ensuring consumer trust based on consistent gemological grading standards.
The Role of GIA-GTL in Gemstone Grading
GIA-GTL uses rigorous scientific methods to grade diamonds and gemstones. They assess natural and lab-grown diamonds, colored stones, and pearls with meticulous precision. Each gemstone undergoes thorough analysis, ensuring the highest level of accuracy.
The Four Cs: Diamond Grading 101
The GIA is world-renowned for its diamond grading system, based on the Four Cs: Carat, Cut, Color, and Clarity. These criteria provide a universal language for diamond quality, and GIA-GTL's grading reports are trusted worldwide.
- 1Carat: A diamond's weight is measured in metric carats.
- 2Clarity: The presence of internal or external imperfections, graded from Flawless (no inclusions) to Included (inclusions visible to the naked eye).
- 3Color: The absence of color in white diamonds is described from D (colorless) to Z (light yellow).
- 4Cut: The precision of facet structure, consistency of facet shape, and alignment. The overall cut quality is not dependent on the diamond's shape, which is not a factor.
GIA-Graded Diamonds Vary In Quality
Many people ask whether GIA-graded diamonds are of good quality. The answer is more complex because the GIA Gem Trade Laboratory (GIA-GTL) evaluates diamonds of all gem-quality grades.
Under those conditions, a GIA-graded diamond can exhibit low-to-high characteristics on the grading scale. Consumers must understand the GIA grading scale and determine the most desirable factors.
A GIA diamond grading report provides a detailed analysis of a diamond's characteristics based on assessments of the Four Cs: Carat, Cut, Color, and Clarity.
A GIA diamond grading report is not a certificate or warranty. It does not indicate whether a diamond looks good or bad. Instead, it describes the specific attributes of the diamond submitted for grading.
GIA-GTL Report for Black by Brian Gavin Diamond.
Quality Spectrum of GIA-Graded Diamonds
Diamonds graded by the GIA can vary significantly in quality. For example:
GIA Excellent Diamond Grading Report
The GIA grading report accurately describes a diamond's characteristics but does not deem them good or bad. In that case, it's up to the buyer to decipher the information and make that determination.
From our perspective, characteristics like color and clarity are primarily a matter of preference. In contrast, we recommend a narrow proportions field due to its effect on light return and performance.
The GIA Excellent-cut rating encompasses a broad range of proportions outside our preferences. Focusing on the center target range is essential to maximize light return and ensure a balance of brilliance and dispersion.
Our Recommended Round Brilliant Proportions
The pavilion angle on a diamond's lower half dictates the light return volume. Meanwhile, the crown angle on the top half of the diamond determines the balance of brilliance and dispersion.
The table facet diameter and total depth measurements factor into a diamond's appearance but are less critical than the crown/pavilion angle offset. With this in mind, we recommend strictly adhering to this range:
It's essential to remember that a diamond's proportions set the stage for light performance but do not guarantee superior results. The additional insight that ASET and Hearts & Arrows Scope images provide is essential for determining light performance.
GIA-GTL's Advanced Technology
GIA-GTL employs state-of-the-art technology in its evaluations, including microscopes, diamond grading lights, and computerized proportions analysis. Its advanced equipment ensures consistent and accurate grading.
From our perspective, GIA's crown jewel is the Angular Spectrum Evaluation Tool (ASET) acquired from the AGS Laboratory. It provides an accurate and consistent method for grading diamond light performance.
The GIA-GTL offers ASET as a supplementary service for an additional charge. Unfortunately, most diamond cutters choose not to include ASET on their GIA lab reports, most likely because it negatively affects their diamonds' production quality.
AGS Ideal Cut Report for Black by Brian Gavin Diamond.
GIA's Angular Spectrum Evaluation Tool (ASET)
The GIA-GTL acquired ASET from the AGS Laboratory at the end of 2022 when the AGSL closed. As an optional service, the GIA scans diamonds using ASET and issues an AGS Ideal Report.
The optional ASET-based AGS Ideal Report is only available when the diamond is submitted to the GIA for grading. Under those circumstances, a digital AGS Ideal Report, including the ASET map, is available via the GIA Report Check tab.
Not surprisingly, the ASET map shown on GIA's AGS Ideal Report for this Black by Brian Gavin diamond confirms its outstanding cut quality. The ASET map shows that brightness and contrast are evenly distributed. Read our ASET Tutorial to understand the depth of insight this valuable tool provides.
GIA Report Check with AGS Ideal Report
The Importance of GIA-GTL Reports
A GIA-GTL diamond grading report comprehensively describes the gemstone's characteristics. These reports instill confidence in buyers, ensuring they know a diamond's attributes before purchasing.
It's essential to understand that the GIA-GTL issues diamond grading reports, not certificates. As such, the report describes the diamond's characteristics when submitted for grading.
Despite erroneous trade references to diamond grading certificates, the GIA Gem Trade Laboratory does not warrant or certify a gem's value. A statement on the back of GIA diamond grading reports clearly states it is not a certificate.
GIA's Role in Ensuring Transparency
The GIA does not endorse or guarantee the quality of the diamonds it grades. It provides an unbiased, accurate assessment of a diamond's grading characteristics. This transparency helps consumers understand what they are purchasing, but it does not judge subjective quality.
When you see a GIA grading report, you know the diamond's characteristics have been meticulously evaluated. However, the quality of the diamond itself depends on its specific characteristics. Our diamond concierge service can help you interpret the report's attributes before purchase.
Colored Stone and Pearl Grading
GIA-GTL also excels in grading colored stones and pearls. Its advanced techniques and expertise ensure precise evaluations. The GIA-GTL analyzes factors such as hue, tone, and saturation in colored stones and assesses the millimeter dimension (size), shape, color, luster, and surface condition of pearls.
GIA-GTL and Ethical Practices
GIA-GTL upholds strict ethical standards. Their commitment to transparency and integrity makes them a trusted pillar of the gem industry.
Education and Training
The Gemological Institute offers extensive courses in gemology, fostering the next generation of gem experts. Its training programs are respected worldwide and produce highly skilled professionals known as GIA Graduate Gemologists.
Conclusion
The GIA Gem Trade Laboratory is a pillar of excellence in the gem industry. Its dedication to accuracy, integrity, and education ensures it remains the gold standard in gemstone grading.
A GIA-GTL report provides a consistent basis for comparing characteristics, such as the 4Cs, when purchasing a diamond. However, verifying the diamond cut quality is essential if performance is a concern.
The GIA cut grade generally considers proportions, polish, and symmetry. However, it does not account for optical precision, which can only be assessed using an ASET Scope and Hearts & Arrows Scope.
At the time of this writing, Brian Gavin Diamonds and Whiteflash include the optional ASET data on their GIA diamond grading reports. GIA's ASET map is a computer-generated rendering, not an actual photograph. We recommend using it with the reflector scope images these vendors provide on their diamond details pages.
ASET for GIA-graded Brian Gavin Black Diamond.