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BACKGROUND Through visiting the jadeite market, the existence of inorganic material-filled jadeite is known, but there is a lack of identification basis due to rare references. OBJECTIVES To understand the identification characteristics of inorganic material-filled jadeite. METHODS Two types of inorganic materials, water glass and silica sol, were used to fill low-grade jadeite in the simulation experiment. Conventional gemological tests, fluorescence image observation with DiamondViewTM, Fourier transform infrared (FTIR) spectroscopy, and laser-induced breakdown spectroscopy (LIBS) were used to test the inorganic filled jadeite samples. RESULTS The transparency, color, density and structure of jadeite were improved after filling. Under the DiamondViewTM, the jadeite particles in the sample showed green fluorescence, and the filling around the cracks and between the particles displayed blue fluorescence with non-uniform distribution. Mid-infrared reflectance spectrum analysis showed that the spectra of silica sol and water-glass were slightly different from each other. The absorption peaks of the samples filled with inorganic materials at 1162cm-1, 1070cm-1, 949cm-1, 579cm-1, 529cm-1 and 470cm-1 gradually weakened, and the peak shape gradually became smooth or disappeared. In addition, the differences between the jadeite and inorganic filled jadeite can be determined by the near-infrared spectral morphology and the shape of the absorption peak changed in the range of 7062cm-1, 5204cm-1 and 4537cm-1. The laser-induced breakdown spectroscopy demonstrated that the content of the silicon in the jadeite filled with silicon sol or sodium and potassium water-glass was higher. The high potassium content was an important feature for the jadeite filled by sodium and potassium water-glass. CONCLUSIONS The samples effect of the simulation experiment needs to be improved, but the identification characteristics of the filled jadeite with inorganic materials are recognized, which has caused a further breakthrough in the enhancement and treatment of jadeite identification.

BACKGROUND The Marange diamond deposit in Zimbabwe is characterized by producing mixed-habit (octahedral and cuboid) diamonds. Graphite inclusions in these diamonds only exist in cuboid sectors. The morphological and distributional characteristics of graphite inclusions and the abnormal birefringence and strain characteristics of diamonds can reflect the geological process experienced by diamonds from the beginning of crystallization to being transported to the Earth's surface. Therefore, the study of diamonds and graphite inclusions in Zimbabwe can provide comparative data for diamonds from other deposits. Besides, due to the peculiarity of growth habits, detailed analysis would be of great value to help understand the behavioral differences of diamonds with different growth habits in geological processes. OBJECTIVES To determine if graphite inclusions in Zimbabwean diamonds are syngenetic or epigenetic, and to reveal the relationship between graphite inclusions and the infrared absorption spectrum, Raman scattering spectrum as well as birefringence and strain characteristics of diamonds. METHODS The growth structure and growth sectors of Zimbabwean diamonds were observed by DiamondViewTM image system. The morphological and distributional characteristics of graphite inclusions and abnormal birefringence in diamonds were analyzed by scanning electron microscopy (SEM) and polarized light microscopy. Analysis of distribution and relative concentration of impurity elements in different growth sectors was conducted by infrared spectroscopy. Strain characteristics of diamonds in different growth sectors were analyzed by Raman spectroscopy and projection diagram of corresponding results. RESULTS Graphite inclusions in cuboid sectors of Zimbabwean diamonds were syngenetic-epigenetic inclusions located in directional elliptical cracks. According to infrared spectra of different growth sectors, cuboid sectors showed stronger infrared absorption related to elemental hydrogen, while octahedral sectors showed stronger absorption related to elemental nitrogen. This enrichment of different impurity elements leading to abnormal birefringence was mainly related to cracks and different growth sectors in diamond. The Raman shift of LO=TO band in octahedral sectors was 1332.05-1332.20cm-1, the FWHM was 4.21-4.37cm-1, which corresponded to stress of 0.06-0.27GPa. The Raman shift of LO=TO band in cuboid sectors was 1331.93-1332.47cm-1, the FWHM was 3.67-4.08cm-1, which corresponded to stress of 0.01-0.64GPa. In general, the residual stress and strain were greater in cuboid sectors. CONCLUSIONS The determination of the orientation of graphite inclusions in mixed-habit diamonds in Zimbabwe, provides new evidence to prove their syngenetic-epigenetic nature, and reveal the difference in the strain characteristics of diamonds in the two growth regions. This research is helpful for understanding the formation environment of diamonds in Zimbabwe and of different diamonds. The differences in physicochemical properties are of great significance.

Hydrogen-related infrared absorption bands in natural diamonds have been extensively investigated and widely used to identify natural, treated, and synthetic diamonds grown by high pressure and high temperature (HPHT) and chemical vapor deposition (CVD) techniques. However, the evolutional behavior of the hydrogen-related defects and the relationship between the hydrogen-related and nitrogen-related defects in natural and HPHT-treated Ib diamonds are unclear. In this article, the hydrogen-related defects, particularly the infrared absorption bands of 3107 cm−1 and 3143 cm−1 in natural type Ib diamonds and HPHT-treated natural diamonds, were systematically investigated using spectroscopic techniques. It was found that the 1405 cm−1 absorption intensity was directly proportional to the 3107 cm−1 absorption intensity; the 3143 cm−1 absorption intensity increased with the increase in the 3107 cm−1 absorption intensity, but there was no strict linear relationship between them. The 3143 cm−1 band was not only related to the intensity of the 3107 cm−1 but also related to the value of NC/NA in natural diamonds. When the value of NC/NA was less than one, the 3143 cm−1 band was more pronounced. After high-temperature annealing, the absorption intensities of the 3107 cm−1 and 3143 cm−1 in natural type Ib diamonds became stronger. However, in HPHT synthetic diamonds, only a 3107 cm−1 defect was introduced with the increase in the A centers in the diamonds. The difference and the detectability of the 3143 cm−1 and 3107 cm−1 bands investigated could be efficiently used to identify natural type Ib diamonds from their counterparts, including the synthetic diamonds and the HPHT-treated diamonds. [ABSTRACT FROM AUTHOR]

Natural blue sapphire is a gem species of corundum, which has high economic value due to its beauty and rarity. Color is the most important factor affecting the price of sapphire and mainly caused by trace elements. However, there is little quantitative data currently available to demonstrate the correlation between trace elements and colorimetric parameters of natural blue sapphire. In this study, the UV‐Vis‐NIR spectra and colorimetric parameters were collected by UV‐Vis‐NIR spectrophotometer while the chemical composition was analyzed by laser‐ablation inductively coupled plasma mass spectrometry. The results show that the content ratio of (FeOT + TiO2)/MgO has negative correlation with b* but positive correlation with Cab*, illustrating its obvious effect on the blue color saturation of natural blue sapphire. In addition, the existence of Cr can produce purple hue and the content of Cr shows positive correlation with hue‐angle hab only in the low range (5‐15 ppm), which implies the content of Cr has a limited influence on the hue of natural blue sapphire and the effect may be more complicated as the content of Cr increases above 15 ppm. This investigation can provide quantitative data for scientific color grading and additional applications of natural blue sapphire. [ABSTRACT FROM AUTHOR]

This study investigates nonisothermal co-drying kinetics of two typical biomasses (cornstalk and red pine) with lignite in the presence of a nitrogen atmosphere using a thermal gravimetric analysis technique. The drying rate can be increased by either decreasing the blending ratio of biomass or increasing the heating rate. The activation energies of cornstalk/lignite blends and red pine/lignite blends in the two falling rate periods are less than that of their parent samples. In the first falling rate period, the dominant mechanisms of drying for lignite are described by the Avrami–Erofeev equation (n = 1.5), while the mechanisms for the cornstalk, red pine, and mixture samples are fitted to the Mample equation (n = 1.0). In the second falling rate period, the mechanisms are described by the Avrami–Erofeev equation (n = 1.5 orn = 2.0). The general kinetic compensation effect correlations are obtained for all samples within heating rates of 10–30°C/min. Significant synergistic interactions between the Chinese lignite and cornstalk or red pine are detected during co-drying. [ABSTRACT FROM AUTHOR]