The Gemological Institute of America (GIA) recently examined two rare natural diamonds with star-like cloud inclusions at its Carlsbad office.
These diamonds, known as “asteriated” or “star” diamonds, are unusual due to their size and preserved natural forms. According to the GIA’s latest issue of Gems & Gemology, the stones weigh 8.14 and 8.57 carats each. Their light-brown cloud inclusions are the result of high concentrations of hydrogen and nickel during their formation. The GIA also suspects the presence of graphite in the diamonds.
The 8.14-carat diamond retained much of its rough form on one side, while the other side was sliced to reveal its inclusion pattern. The rough surface showed brown radiation stains, suggesting it underwent natural alpha irradiation and subsequent annealing. The 8.57-carat diamond was polished with bruted edges.
Both diamonds exhibited green fluorescence under long-wave UV light, a common feature in asteriated diamonds. The GIA employed advanced techniques, including X-ray computed microtomography and Fourier-transform infrared spectroscopy, to analyze these unique gems.
