Editor’s Note
This case highlights the risks of purchasing diamonds from unofficial channels. As detailed, a seemingly good deal turned out to be a synthetic stone with a counterfeit GIA inscription. We urge consumers to always verify certifications through official channels and purchase from reputable jewelers.
A consumer, after self-studying jewelry knowledge online for a long time, found a channel to purchase a 1-carat diamond below market price. Before resetting it, they had it tested, only to discover the diamond was fake! Upon examination under magnification, anomalies were found. The stone showed no 415nm line under instruments, and under high magnification, the GIA inscription on its girdle appeared as a “solid black line.” Authentic GIA-certified diamonds come with a GIA Diamond Dossier® and have the certificate number laser-inscribed on the girdle. Crucially, the original laser inscription for the “GIA” part features double lines and is hollow. Therefore, the diamond in question was essentially determined to be a CVD synthetic diamond with a counterfeit inscription mimicking a natural diamond’s GIA number.
Such incidents are not new in the jewelry industry. On November 13, 2017, GIA’s Carlsbad laboratory identified a 1.76-carat HPHT (high-pressure, high-temperature) synthetic diamond with a color grade equivalent to F and clarity equivalent to VS1. Its girdle was inscribed with the certificate number “GIA 217124.” However, the genuine GIA 217124 corresponds to a 1.74-carat, D-color, VVS1 clarity, Type Ia natural diamond certified in 2015. Lab technicians found discrepancies in weight, color, and clarity compared to the records. Detailed testing confirmed it as an HPHT synthetic diamond, with key evidence including:
– Strong fluorescence and phosphorescence under DiamondView.
– Infrared absorption spectrum indicating a Type IIb diamond.
– Visible growth structure characteristics typical of HPHT synthetics.
– Mismatch in the style and font of the laser inscription compared to the original.
In 2018, the National Gemstone Testing Center (NGTC) Shenzhen Laboratory discovered a 3.10-carat CVD synthetic diamond ring during routine inspection. Its girdle was inscribed with a foreign lab’s certificate number “XXX 51819XXXXX.” Verification showed severe discrepancies with the online electronic certificate data, and the characteristics and locations of inclusions were markedly different. This was a case of counterfeit inscription涉嫌 “套证” (certificate swapping). The round brilliant cut diamond had F-G color and VS clarity. Under a gem microscope, feather inclusions were visible in the crown. Under DiamondView, it showed moderate green fluorescence with blue linear fluorescence and weak phosphorescence—features not distinctly different from some natural diamonds. Spectroscopic tests confirmed it as a Type IIa diamond with an abnormally strong Si-V defect line, characteristic of CVD synthetic diamonds. NGTC concluded it was a CVD synthetic diamond ring with a counterfeit lab inscription,涉嫌套用天然钻石证书 (suspected of using a natural diamond certificate).
Previously, the NGTC Beijing Laboratory received a “diamond” ring sent by a logistics client. Comprehensive testing identified it as a laboratory-grown diamond. Uniquely, the girdle inscription on this stone counterfeited both the NGTC Shanghai Laboratory inscription and a GIA inscription. Using analysis methods including infrared spectroscopy, UV-Vis absorption spectroscopy, magnification, fluorescence imaging, and photoluminescence spectroscopy, NGTC Beijing ultimately determined the sample was a laboratory-grown diamond.
In recent years, such certificate-swapping incidents have become increasingly rampant, with the proportion of counterfeit GIA-certified diamonds on the market also rising.
Therefore, it is recommended that both merchants when sourcing and consumers when purchasing diamonds or colored gemstones should first verify the certificate number on the issuing institution’s official website. After confirming the certificate’s existence, carefully inspect the physical certificate—counterfeit certificates often have differences in print clarity, font size, and paper quality. If still unsure, one can take the item with valid proof of purchase and the certificate to a national authoritative quality inspection agency for re-examination.
The example of “self-studying to buy diamonds” also indirectly proves the unreliability of this approach. Without sufficient professional knowledge and practical experience, it is advisable to choose正规靠谱的珠宝商 (formal and reliable jewelers) when selecting diamonds, colored gemstones, and other jewelry.