The Gemological Institute of America (GIA) recently examined two diamonds, submitted separately, which both contained star-shaped patterns stemming from clouds of dark micro-inclusions.
The first stone was a 3.45-carat diamond from Zimbabwe, which had been partially faceted with rough surfaces preserved along the edges, according to an article in the Fall issue of Gems & Gemology, the institute’s quarterly journal. The stone had six lobed asteriated inclusion sectors, with a six-sided pattern visible in the center. Based on a visual examination, the GIA concluded graphite inclusions within the diamond formed the star pattern.
While inclusion patterns producing a star or triangle shape when viewed through the polished windows of a diamond are not unusual, this one had graphitic clouds radiating outward, starting from the central figure in a pattern the GIA had not seen before, it said.
Meanwhile, the second diamond, a 13.89-carat stone, was faceted and displayed dark clouds of micro-inclusions with clear openings in the center of the main facets. However, hydrogen clouds led to these inclusions, with nickel-related peaks that caused the clouds to fluoresce green when exposed to long-wave UV. The diamond contained etch channels passing through clear openings of the clouds, which may have come from radioactive fluids entering them while the stone was still in the earth, the GIA explained.
“Although both of these diamonds have similar infrared spectra, radiation staining, and the presence of dark micro-inclusions, the diamonds manifest these characteristics in different ways,” the institute added. “They provide another example that all natural diamonds have their own journey and origin story.”
BRON: Rapaport 10-9-2025
