The IGI has detailed a method for screening each colour category, using a combination of advanced techniques as part of a procedure known as an ‘IGI D-check’.
CEO Tehmasp Printer said that as fancy-coloured diamonds become more popular, offering the industry peace of mind with procedures such as this was paramount.
“With lab-grown fancy colour diamonds gaining momentum and the differential pricing being substantial, it’s imperative that the screening is done by a reputable laboratory,” said IGI CEO Tehmasp Printer.
“We had a few cases in recent times where there has been a contamination of natural fancy colour pink diamonds mixed with lab-grown pink diamonds.”
Printer explained that screening devices for natural and lab-created diamonds commonly work on the principle of photoluminescence, where signature fluorescence and phosphorescence exhibited by a diamond is captured under ultraviolet light of a shorter wavelength.
An issue arises, however, as fancy colour diamonds do not behave in the same way as colourless and near-colourless diamonds.
Lab-created fancy colour diamonds are treated with irradiation, heat and pressure, altering their fluorescence and phosphorescence. Many screening machines, therefore, cannot effectively separate between natural and lab-created diamonds.
Printer said that by using advanced techniques such as photoluminescence spectroscopy and Fourier transform infrared spectroscopy, as well as magnification, the IGI is now able to distinguish between natural and lab-created stones.
“IGI has developed the D-check in the interest of transparency and peace of mind for the industry and consumers alike,” he added.
“Our commitment to accuracy and transparency in the certification process is reflected in strict adherence and regular calibration of our international standards and testing methods across our worldwide locations.”
The IGI said this approach can successfully differentiate between loose natural and lab-created fancy colour diamonds and stones set in finished jewellery.
In a similar matter earlier this year, the IGI announced the discovery of a 6.01-carat lab-created diamond marked with a laser inscription for a natural stone.
The diamond’s carat weight, physical description, and inscription were consistent with those of a natural diamond graded by the Gemological Institute of America.
More reading
Fresh allegations of lab-created diamond fraud emerge
Blue diamonds continue to impress at auction
Yellow diamond dazzles collectors in New York
Fancy colour diamonds light up auctions
Fraud: Concern spreads amid lab-created diamond controversy
Jewellery designers around the world put to the test
Blackstone purchases International Gemological Institute