Historically, diamond grading laboratories like the Gemological Institute of America (GIA) and American Gem Society (AGS) have graded diamond color by human eyes comparing diamonds with “master stones.” A new laboratory, the Dubai-based International Diamond Laboratories (IDL), has developed a new device called the Color Meter, which is designed to accurately color grade diamonds.
With human eyes examining diamonds there are many factors that can influence the accuracy of color grading.
- Daylight varies from country to country and hour to hour during the day
- Clouds, pollution and other atmospheric conditions are ever changing
- Light bulbs producing “daylight” spectrum of light are inconsistent
- Eyestrain can change perceptions over time
- Surroundings, including cloths, skin tone, walls, etc. can vary
Human bias is a big factor in judging color. It is no fluke that certain grading laboratories (EGL and IGI for example) are often off in color grading accuracy. The training, supervision, and motivation at those laboratories tend to be lenient in color grading, which benefits the retailers that will ultimately sell the diamonds.
Providing accurate, consistent color grading will mean big changes for the diamond industry if widely implemented. The big difference between the major diamond grading laboratories tends to be in grading color. While all laboratories claim to adhere to the GIA color grading standards, not all laboratories are accurate in applying those GIA standards to the diamonds they are grading. For example, we have seen EGL graded diamonds that are 1 to 3 color grades off the GIA color grade.
What happens when diamond color grading becomes mechanized and accurate? Consumers are the big winners and jewelry stores who sell EGL or IGI graded diamonds lose one of their big money makers. Today many consumers assume that color grading is consistent between laboratories and they think they are getting a “deal” with their EGL or IGI graded diamonds. The reality is they are just paying for a lower color diamond than is represented on the grading report. If color grading is accurate and consistent in the future, the wholesale price for diamonds will be consistent between the grading laboratories and retailers will no longer be able to use the cheaper EGL or IGI graded diamonds to bolster their profit margins.