De Beers does not providegrading reports for its Lightbox lab-grown diamonds, leading to much speculation about their quality. A recent evaluation by a Gemological Institute of America (GIA) scientist found that a pair of quarter-carat Lightbox white stones would likely be graded G VS1.
The findings were written up as a Lab Notefor GIA’s Winter 2018 Gems and Gemology.
After examining two Lightbox round diamonds intended for a pair of earrings—one at 0.24 ct., the other at 0.26 ct.—research scientist Sally Eaton-Magaña said the cutting on the stones would receive “excellent” and “very good” grades, respectively. The two samples were obtained from a “third-party vendor,” the note said.
Interestingly, the Lightbox logo, laser-inscribed beneath the table facet, knocked down the clarity of both stones, which otherwise would be considered VVS, Eaton-Magaña wrote.
The two stones were grown with the chemical vapor deposition (CVD) method and do not show any traces of post-growth HPHT (high pressure, high temperature) processing. The GIA says that 75 percent of the near-colorless CVD material it has examined has been HPHT treated after growth.
The Lab Note said that, based on Lightbox promotional literature, its pink and blue lab-growns “have an appearance that is unusual among natural-color diamonds and are unlikely to ever be perceived as a natural-color product.” The colorless Lightbox samples are more difficult to distinguish from mined gems but can be identified as CVD-grown by spectroscopic techniques, DiamondView testing, and the internal inscription, it said.