GIA Grades Synthetic Diamond with Blue Band

The Gemological Institute of America (GIA) recently examined a 1.09-carat diamond grown by chemical vapor deposition (CVD) that displayed a blue band. 

A customer recently submitted the D-color synthetic diamond to the GIA’s laboratory in Mumbai. The coloring was likely a result of uncompensated boron concentration, according to an article in the Spring issue of Gems & Gemology, the institute’s quarterly journal.  

Boron doesn’t often cause blue color in CVD-grown diamonds, because it is usually found in only about 5% of these stones, and then in low concentrations. However, it more commonly leads to a blue hue in diamonds produced using the High Pressure-High Temperature (HPHT) method, where it is detected more often.  

The diamond the GIA graded underwent post-growth HPHT annealing, the lab found. 

“It is unclear whether this blue layer with a sufficiently high concentration of uncompensated boron to show color was intentionally created by the manufacturer or resulted from an accidental disruption of the standard growth recipe,” the GIA noted.