IGI Sees Largest and Multicolored Lab-Grown Diamonds

By Rob Bates | June 12, 2023

The International Gemological Institute (IGI) recently analyzed and graded a polished lab-grown diamond over 50 carats—the largest on record—as well as another novelty, a multicolored lab-grown.

The 50.25 ct. diamond, named “Shirpa,” is a type IIa emerald cut measuring 22.95 x 18.45 x 11.57 mm, with G color, VS2 clarity, and excellent cut, polish, and symmetry. It was grown and polished over a period of six months by Mumbai-based Ethereal Green Diamond, using the chemical vapor deposition method. No value was given for the stone.

IGI says this recent discovery was the first to pass the “half century” benchmark in carats. In May, GIA had graded a 34.59 ct. emerald-cut CVD-grown diamond, which was the biggest diamond that lab had ever seen.

In addition, IGI has analyzed a piece of 10.96 ct. rough and a 4.38 ct. lab-grown diamond that display color zones of both blue and yellow.

The diamonds were grown using high pressure high temperature (HPHT) by Meylor Global, a Ukrainian company that created the multicolored gems in honor of the country’s blue-and-yellow flag.

The 4.38 carater is a polished radiant cut measuring 9.93 x 8.88 x 6.21 mm, with VVS2 clarity and very good cut. Its color is described as fancy deep greenish blue.

Both gemstones finished as-grown with no evidence of post-growth treatment. IGI spectroscopy classified them as type IIb, with traces of nitrogen in the yellow areas. Meylor said it used boron doping to create the blue color.

“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 Global, in a statement. “Once we understood the physics, we used precise nitrogen and boron content, coupled with strictly controlled pressure, temperature, and growth rates to produce this [diamond].”

It plans to sell the diamond at $4,500 a carat.