Going Better: GIA Uses X-Rite Tools to Ensure Gem Color Is Accurately Certified
Because two gemstones of the same weight can have thousands of dollars in difference in value due to the difference in color, jewelers and wholesalers who buy and sell gemstones need to ensure that the products they hold have been accurately tested by qualified personnel under accurate lighting. rating.
Because of the difference between "expensive" and "priceless" jewelry, jewelers and wholesalers have turned to GIA (Gemological Institute of America) laboratories to provide accurate identification and grading of diamonds, colored gemstones and pearls.
When encountering color-related issues, GIA turned to X-Rite Inc. for our expert opinion on color vision evaluations by grading technicians and in providing good lighting conditions for accurate gemstone identification.
John King, quality officer at GIA, which has jewelry identification and grading laboratories in New York City, Carlsbad, California, Bangkok, Hong Kong, Mumbai, Johannesburg, and Botswana's capital Gaborone, said gemstones were exposed to different lighting conditions. There will be different shades, and the difference is huge.
Colored gemstones will look different under natural light depending on a number of factors such as time of day, season, climate, and the city where the gemstone is inspected. For example, a sapphire may appear brilliantly saturated in midday sunlight but become relatively dull in the early morning or evening hours.
Given that natural daylight is highly variable and not available everywhere, GIA employs calibrated Macbeth Judge II light boxes made by X-Rite in its laboratories. The Judge II accurately simulates midday sunlight and sunrise and sunset light, as well as the "normal" fluorescent and incandescent light sources one might find in a retail store or home. It also regulates the invisible ultraviolet light that is found in natural sunlight and can make certain gemstones shine even more.
“When we were thinking about improving the gemstone color grading system in the early 1990s, we looked at a lot of testing environments,” King said. Commercial transactions. The Judge II can be used all over the world and is well known in the industry as a good fluorescent light source."
While most of GIA's colored gemstone identification work is done at laboratories in Carlsbad, New York City and Bangkok, King said the agency has begun visiting laboratories in other regions, a move that will allow Judge II to be used more geographically . “We took the equipment along the way, simulating the qualifications done in the lab,” he said, “confirming that the Judge II was very useful in these demonstrations.”
Light source is the variable in the precise gem grading process and needs to be precisely regulated, King said. If technicians are to grade gemstones, they need to have normal or very good color vision themselves, and surprisingly, some people have some form of color vision deficiency. Research shows that about 1 in 12 men has some form of color blindness, while 1 in 255 women suffers from it.
“Gemstones can vary in color sometimes very slightly, but our work requires us to be accurate and consistent,” King said. "Our graders have all passed rigorous tests to ensure their visual acuity is up to the job requirements."
For would-be graders, GIA 's primary method of evaluation is the use of the Munsell FM 100 Color Vision Testing System (Farnsworth Munsell
100 Hue Test), a "color IQ test" created by X-Rite that helps companies classify employees' color vision as low, medium, or high. People who take the color vision test can usually complete the Farnsworth Munsell 100 Color Vision Test within 20 minutes, and it takes only 5 to 10 minutes to learn how to administer the test. Because the test is quick and efficient, businesses typically use it annually to test employees to assess whether their sensitivity to color distinctions has changed over time.
Simplicity is the hallmark of the Farnsworth Munsell 100 Color Vision Testing System. The test implementer puts out 4 test trays, and there are 85 random color blocks on the trays. Each patch has a different hue, but has the same lightness and saturation values. The test participants were tasked with placing the color patches in the correct order of hues. The score is based on the number of misplaced color blocks, and the lower the score, the stronger the ability to distinguish color difference.
Each gemstone is usually independently graded by several GIA graders, and until they agree on the quality of the gemstone, it is not known where the gemstone came from, its owner or anyone else's grading results.
The actual process of identifying a gemstone in the lab may have taken only a few minutes, but each gemstone was identified multiple times by different people. Stones placed in light boxes are barcoded or otherwise anonymized and compared to GIA's existing samples.
Considering the potential value of all the gemstones it takes over, GIA adopts multi-person identification and anonymous labeling measures, which can ensure that each gemstone can be fully inspected, and its value assessment must be fair and objective.
“GIA is a standards body, so the importance of continuity in what we do and how we do it cannot be overemphasized,” King said. "Graders work independently, inspect and re-inspect, all to maintain the quality and integrity of the work."
"X-Rite's tools help us get accurate color shade assessments at all times," he added.
