Recently, the New York laboratory examined a pink rough sample submitted for identification. The 6.06 ct specimen (9.19 × 8.52 × 10.67 mm) appeared to be a resorbed octahedral crystal (figure 1, left). Although its surface displayed etched trigons and rounded faces—features commonly associated with natural rough diamond crystals—the crystal also exhibited unusually sharp edges (figure 1, right). Initial spectroscopic analysis suggested that the Fancy pink color resulted from a multi-step treatment process involving high-pressure, high-temperature treatment, artificial irradiation, and moderate temperature annealing. However, subsequent testing revealed that the diamond was not of natural origin. Instead, it was a diamond grown by the chemical vapor deposition (CVD) method, fabricated into a natural-looking octahedral morphology and further treated to produce trigon etch features on only one facet, closely mimicking the appearance of a natural rough diamond.
Prior etching experiments have been conducted on both natural and laboratory-grown diamonds to reproduce the development of surface etch features using water-carbon dioxide mixtures, carbonatitic fluids, silicate fluids, and carbon-oxygen-hydrogen fluids. Such experiments are typically performed at pressures of 5–8 GPa and temperatures of 1100°–1600°C (A.F. Khokhryakov et al., “Experimental modeling of diamond resorption during mantle metasomatism,” Minerals, Vol. 12, No. 4, 2022, article no. 414). The etching observed on this CVD sample is consistent with formation under similar conditions.
Infrared absorption spectroscopy indicated that the diamond was nominally type IIa; however, a very weak 1344 cm–1 feature associated with isolated nitrogen was observed. Natural type IIa diamonds typically exhibit irregular crystal morphology rather than well-formed octahedral crystals. Therefore, the combination of a type IIa classification and a distinct octahedral morphology immediately raised questions about the stone’s origin. The visible/near-infrared (Vis-NIR) absorption spectrum displayed the characteristic negatively charged silicon-vacancy ([Si-V]–) doublet, confirming a CVD-grown origin (figure 2). The spectrum also exhibited treatment-related absorption features, including bands at 575 nm (NV0), 594 nm, and 637 nm (NV–), consistent with irradiation and annealing. Similar features were reported in a multi-treated natural rough diamond (Spring 2026 Lab Notes, pp. 68–69). DiamondView imaging revealed multiple growth layers and distinct interlayer boundaries (i.e., planes between successive growth layers), accompanied by fine striations within the growth layers (figure 3, left). Notably, the etch markings were aligned with the striation directions, indicating that the surface features appeared to be controlled by the underlying growth structure (figure 3, right). Collectively, these observations confirmed that the diamond was a CVD synthetic that had been treated to produce its pink color.
Although the surface exhibited etched trigons—features typically regarded as indicators of natural origin—comprehensive testing demonstrated that it was, in fact, a treated CVD-grown diamond. This case highlights the importance of advanced analytical techniques in diamond identification. Reliance on surface morphology alone can be misleading, whereas spectroscopic analysis and DiamondView imaging provide definitive evidence for accurately determining a diamond’s origin.
This is the first case documented by GIA of a CVD-grown diamond that was deliberately modified to produce a natural-looking octahedral crystal morphology; a near-colorless CVD-grown specimen has been previously reported (Spring 2026 Gem News International, pp. 99–101). The finding demonstrates an increasingly sophisticated approach to simulating the appearance of natural rough diamonds and underscores the need for comprehensive laboratory analysis when determining diamond origin.
Kyaw Soe Moe is supervisor of analytics, and Wuyi Wang is senior vice president of research and identification, at GIA in New York.
Recently, the New York laboratory examined a pink rough sample submitted for identification. The 6.06 ct specimen (9.19 × 8.52 × 10.67 mm) appeared to be a resorbed octahedral crystal (figure 1, left). Although its surface displayed etched trigons and rounded faces—features commonly associated with natural rough diamond crystals—the crystal also exhibited unusually sharp edges (figure 1, right). Initial spectroscopic analysis suggested that the Fancy pink color resulted from a multi-step treatment process involving high-pressure, high-temperature treatment, artificial irradiation, and moderate temperature annealing. However, subsequent testing revealed that the diamond was not of natural origin. Instead, it was a diamond grown by the chemical vapor deposition (CVD) method, fabricated into a natural-looking octahedral morphology and further treated to produce trigon etch features on only one facet, closely mimicking the appearance of a natural rough diamond.
Prior etching experiments have been conducted on both natural and laboratory-grown diamonds to reproduce the development of surface etch features using water-carbon dioxide mixtures, carbonatitic fluids, silicate fluids, and carbon-oxygen-hydrogen fluids. Such experiments are typically performed at pressures of 5–8 GPa and temperatures of 1100°–1600°C (A.F. Khokhryakov et al., “Experimental modeling of diamond resorption during mantle metasomatism,” Minerals, Vol. 12, No. 4, 2022, article no. 414). The etching observed on this CVD sample is consistent with formation under similar conditions.
Infrared absorption spectroscopy indicated that the diamond was nominally type IIa; however, a very weak 1344 cm–1 feature associated with isolated nitrogen was observed. Natural type IIa diamonds typically exhibit irregular crystal morphology rather than well-formed octahedral crystals. Therefore, the combination of a type IIa classification and a distinct octahedral morphology immediately raised questions about the stone’s origin. The visible/near-infrared (Vis-NIR) absorption spectrum displayed the characteristic negatively charged silicon-vacancy ([Si-V]–) doublet, confirming a CVD-grown origin (figure 2). The spectrum also exhibited treatment-related absorption features, including bands at 575 nm (NV0), 594 nm, and 637 nm (NV–), consistent with irradiation and annealing. Similar features were reported in a multi-treated natural rough diamond (Spring 2026 Lab Notes, pp. 68–69). DiamondView imaging revealed multiple growth layers and distinct interlayer boundaries (i.e., planes between successive growth layers), accompanied by fine striations within the growth layers (figure 3, left). Notably, the etch markings were aligned with the striation directions, indicating that the surface features appeared to be controlled by the underlying growth structure (figure 3, right). Collectively, these observations confirmed that the diamond was a CVD synthetic that had been treated to produce its pink color.
Although the surface exhibited etched trigons—features typically regarded as indicators of natural origin—comprehensive testing demonstrated that it was, in fact, a treated CVD-grown diamond. This case highlights the importance of advanced analytical techniques in diamond identification. Reliance on surface morphology alone can be misleading, whereas spectroscopic analysis and DiamondView imaging provide definitive evidence for accurately determining a diamond’s origin.
This is the first case documented by GIA of a CVD-grown diamond that was deliberately modified to produce a natural-looking octahedral crystal morphology; a near-colorless CVD-grown specimen has been previously reported (Spring 2026 Gem News International, pp. 99–101). The finding demonstrates an increasingly sophisticated approach to simulating the appearance of natural rough diamonds and underscores the need for comprehensive laboratory analysis when determining diamond origin.
Kyaw Soe Moe is supervisor of analytics, and Wuyi Wang is senior vice president of research and identification, at GIA in New York.
