IGI Grades Bicolor Lab-Grown Diamonds

The International Gemological Institute (IGI) has analyzed two lab-grown diamonds containing separate sections of blue and yellow coloring.

The bicolor stones were grown by Meylor Global, a Kyiv-based company, using High Pressure-High Temperature (HPHT), IGI said Saturday. The first stone, a radiant-cut, 4.38-carat, VVS2-clarity polished diamond has a color described as fancy-deep-greenish blue. The 10.96-carat rough diamond also displays specific blue and yellow color zones, the lab noted. The stones’ coloring is a nod to Meylor’s home country of Ukraine.

“The blue and yellow are described as ‘greenish’ because natural and lab-grown fancy-colored diamonds are traditionally assessed with all hues, tones and saturation considered collectively,” said Steve Rees, executive director of IGI’s North American grading lab. “What’s observed here is deliberate, specific color separation…the first of its kind we’ve seen.”

The lab determined traces of nitrogen in the yellow portions of the diamonds using spectroscopy. Meanwhile, Meylor used boron doping to create the blue-colored sections, IGI explained.

“Precise color zoning is the result of years of research and experiments where chemicals and cycling are rigorously controlled,” said Yuliya Kusher, CEO of Meylor. “Once we understood the physics, we used precise nitrogen and boron content, coupled with strictly controlled pressure, temperature, and growth rates, to produce this fascinating mix of bi coloration, corresponding to the Ukrainian national flag.”

Check out the video below to see how the bicolor stones were made:

Image: The rough and polished bi-color diamonds. (International Gemological Institute)