Gemologic and Spectroscopy Properties of Chinese High-Pressure High-Temperature Synthetic Diamond

Compared with the chemical vapor deposition method, the high-pressure and high-temperature (HPHT) method has some advantages, such as fast diamond crystal growth speed, mature technology and easy mass production. HPHT method synthetic diamond is widely used industrially, but gem-quality synthetic diamond from China has rarely been reported. In this work, the gem-quality diamond synthesized by State Key Laboratory of Superhard Materials, Jilin University, China (SKLSHM), using the cubic hinge press equipment by the HPHT method, was investigated by microscopy, field-emission scanning electron microscopy (FE-SEM) and Diamond View observations as well as infrared spectrometer, ultraviolet–visible spectrometer (UV spectrometer) and energy-dispersive x-ray fluorescence tests. FE-SEM observation showed that regular growth steps and obvious growth pits were common on the {100} surface, and they were consistent with the distribution of internal metal inclusions. In most cases, the {111} plane is significantly flatter than the {100} plane, which may be related to the surface atomic state. It also can be seen that the internal metal inclusions are easily aligned along the internal growth boundary,which may be due to the different growth rates of different crystal faces during diamond growth. The fluorescent image under Diamond View shows the special geometric growth zone structure. Cubes, octahedrons and rhombohedral dodecahedrons have different intensities of orange, yellow, blue and other uneven fluorescences, which can be used as the most important diagnostic evidence.