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Research on different types of brown diamonds under high temperature and high pressure and their structural characteristics is one of the most difficult and important issues in diamond research. Previous studies on hydrogen-rich diamond mainly focused on its special growth structure and the formation environment, but rarely on the characteristics of hydrogen-rich diamond after high temperature and high pressure treatment. The spectral characteristics of the hydrogen-rich diamonds before and after high temperature and high pressure treatment, including Infrared Spectra, UV-vis Absorption Spectra, and Photoluminescence Spectra were compared and their identification characteristics were studied. Results show that the spectroscopic features are different for the samples before and after the high temperature and high pressure treatment, epecially for infrared spectra. Absorption peaks related to H and N at 3310 cm-1, 3232 cm-1, 3189 cm-1 weakened obviously or even disappeared. Moreover, the absorption peak at 2688 cm-1 related to isolated nitrogen appeared. In the UV-Vis absorption spectrum, the non-selective absorption in treated brown diamonds became the typical isolated nitrogen absorption, which means that the absorption of 550 nm to shortwave and the absorption of the center of N3 (415 nm) increased obviously. Therefore, the diamond changed from the original brown to yellow. The photoluminescence spectra before and after treatment of diamonds also vary with the types of nitrogen-related defects, peak intensities, and defect combinations. The spectral characteristics obtained not only provide a basis for the accurate identification of yellow, hydrogen-rich diamonds treated by high temperature and high pressure, but also provide a theoretical basis for explaining the change mechanism of hydrogen-and nitrogen-related lattice defects under high temperature.

Quartzite jade is composed of α-quartz and another silica phase, moganite, which forms under low pressure and low temperature conditions. At present, there are few studies on the relationship between the relative content of moganite and the crystallinity of quartzite jade. In this study, some quartzite jade samples from four locations in China(Longling, Yunnan province; Huoshan, Anhui province; Hezhou, Guangxi Zhuang Autonomous Region, and Alxa League, Inner Mongolia Autonomous Region), were analyzed by Raman Scattering Spectroscopy, Infrared Absorption Spectroscopy and X-ray Powder Diffraction techniques. The results showed a negative correlation between the relative content of moganite and the crystallinity of quartzite jade. The higher the relative content of moganite, the lower is the crystallinity index of quartzite jade. The relationship of the intensity ratio of 502 cm-1/465 cm-1 in the Raman scattering spectrum and the crystallinity index of quartzite jade, could be expressed by the equation of Y=-0.36X+6.93(the correlation coefficient is-0.94). This research could not only offer some new ideas about qualitatively estimating the crystallinity of quartzite jade by non-destructive testing methods, but also provide some scientific evidence and theoretical restrictions for qualitatively evaluating quartzite jade.

The key parameter to determine whether jadeitite can be named gem grade jadeitite 'jadeite jade' or not is the content (the mass fraction) of jadeite in jadeitite. So far, most methods to determine the mass fraction of mineral in rock are destructive, which is not suitable in gem detection. Based on the changes of mineral composition and mass fraction of mineral in jadeitite, a non-destructive method by measuring the relative density of jadeitite was established in order to get the mass fraction of jadeite. By Static Water Density Method, 186 pieces of jadeitite samples with relative densities of 3.30-3.24 were divided into groups according to different densities. The main mineral composition and mass fraction of minerals in jadeitite were analyzed by X-ray Powder Diffraction, Manual Heavy-sand Analysis, Electron Probe Microanalysis, Infrared Spectrometry and Raman Spectrometry. The linear relationship between the mass fraction of jadeite and the relative density of jadeitite was statisticstically analyzed. Results show that the main minerals in jadeitite are jadeite, albite, and analcite. As the mass fraction (wA) of jadeite decreases, those of albite and analcime increase, and the measured specific gravities (SG) of jadeitite change accordingly. The relationship between them is wA=1.3454 SG-3.4531 (r=0.9814), showing a good linear dependence relation. Because the measured specific gravity of jadeitite is approximately equal to the theoretical one, mass fraction of jadeite is obtained by measuring the specific gravity of jadeitite. This non-destructive method applies to jadeitite with a specific gravity of 3.3-3.0, jadeite content of 95%-60%, and sum mass fractions of jadeite and albite of 90%-97%.