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.
Image: The lab-grown diamond with the blue band. (Gemological Institute of America)
