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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]

Zultanite is the commercial name of a gem‐quality transparent diaspore that exhibits an obvious color change when exposed to different light sources. It usually appears green under daylight and red under incandescent light. This optical feature makes zultanite valuable, and the study of the spectral characteristics, as well as chemical composition, of zultanite can increase our understanding of the associated color change mechanism. Spectral transmittance curves for zultanite exposed to nonpolarized light emitted by CIE standard illuminants D65 and A show that the color change phenomenon is related to the optical characteristics of light sources. The colorimetric parameters in the CIE 1976 L*a*b* uniform color space system illustrate that the color change exhibited by zultanite is an example of the alexandrite effect, which can be quantitatively described by the significant change of a* and h° parameters. These findings and the results of chemical element analysis by X‐ray fluorescence and X‐ray photoelectron spectroscopy imply that electron transitions between different energy levels involving the 3d orbitals of the trace elements Fe3+ and Cr3+ in zultanite give rise to the relatively high transmittance observed in the green region (around 500 nm) and the orange‐red region (600‐780 nm) of visible light. Thus, the difference in the spectral power distributions of different ambient light sources greatly influence the color of zultanite, making zultanite show green under daylight which is richer in the green light and turns red under incandescent light in which the orange‐red light dominates. Summary: The main contributions of this article can be summarized as follows: The colorimetric parameters of zultanite illustrate that its color change phenomenon is an example of the alexandrite effect.The trace elements Fe3+ and Cr3+ are the essential factors that cause the alexandrite effect, which give rise to the relatively high transmittance observed in the green and orange‐red regions of visible light.This article will inspire deeper research on the optical properties and application of hydroxides. [ABSTRACT FROM AUTHOR]

• The occurrence state of nitrogen getter in diamond crystals is studied. • TiC deposited on the crystal surface to form dendrites pattern. • Ti enters the diamond crystal to form metallic impurities. • This study helps to promote the growth of HPHT-growth IIa diamond crystals. Type IIa diamonds are the most promising gem grade, optical and electronic grade materials with high quality and low defects, however natural type IIa diamonds are rare and therefore the synthetic methods to obtain the high quality type IIa diamonds have been a hot issue. Nitrogen getters play a crucial role in the synthesis of type IIa high temperature high pressure (HPHT) diamonds crystals by reacting with the nitrogen in the system and effectively removing it from the growth process. However, the occurrence state of nitrogen getter introduced after diamond crystal growth remains to be investigated. In this study, a group of HPHT synthetic diamond crystals with different mass fractions of Ti as a nitrogen getter were examined by scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS) and X-ray fluorescent spectroscopy (micro-XRF) to observe the occurrence state of the nitrogen getter Ti within the synthetic diamond crystal, it was found that at the end of crystal growth, There are two forms of Ti present in the process: (i) Ti reacts with C to form TiC, which was deposited on the surface of the diamond crystal in the dendritic pattern, and (ii) Ti enters the diamond crystal to form metallic inclusions. This study provides reliable data to support a comprehensive analysis of the effect of Ti as a nitrogen getter in the growth procession of HPHT synthetic diamond crystal, and it will have a positive effect on the development of synthetic diamond technology. [ABSTRACT FROM AUTHOR]

Trigons on the surface of diamonds are correlated with defects in their crystal lattices. However, due to the rarity of HPHT diamond octahedrons. Few studies have focused on surface features of them. Here, we made detailed observation and description of as-grown surface features on 27 HPHT diamond octahedrons produced from China, and reported new features of jagged steps of trigons, 90° oriented trigons, and residual hillocks on diamonds. The formation of these features was discussed, and the relationships between parameters of trigons and hillocks were thoroughly investigated. It was found that the depth of trigons on these HPHT diamond octahedrons was smaller than 1 μm, and most positive f/b trigons showed the depth limit of 0.2 μm. Besides, correlations between the diameter, depth, and inclination angle of trigons demonstrated that the development of trigons displayed distinctive characteristics in different stages: In the beginning, when the trigons were relatively small (diameter < 5 μm), the increasing rate of depth was larger than that of diameter, while when the trigons enlarged to some extent (diameter > 20 μm), their diameter would develop faster than their depth in the following process. This study expanded our cognition of surface features on diamond, provided solid systematic data for trigons on HPHT diamond octahedrons, and furthered comprehension of the formation process of trigons on the surface of diamonds, which has reference significance for evaluating and improving the quality of synthetic diamond crystals. [Display omitted] • Jagged steps of trigons and trigons with the orientation perpendicular to {111} surface planes were observed. • Residual triangular hillocks with trigons in them were reported. • Relationships between parameters of trigons and hillocks were discussed. • Different developing trends of trigons with different size were determined. [ABSTRACT FROM AUTHOR]

The impurity transition element chromium Cr3+ in ruby can be excited to high energy levels by absorbing visible light. When the excited Cr3+ returns to ground state through an intermediate energy level, the ruby emits red light as fluorescence. The fluorescence of ruby is actually caused by visible light, not by ultraviolet. The color of ruby is attributed to both the absorption and the fluorescence. The spectrum of a natural ruby under visible light is directly measured by a dual integrating sphere spectrometer. The measured spectrum includes both the spectral reflectance and the fluorescence caused by visible light. This study confirmed that the red fluorescence of ruby is indeed caused by visible light, not by ultraviolet radiation. In addition, average color of the ruby is calculated from the measured spectrum, and true color grade is also obtained by the artificial intelligent software of the spectrometer. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 328-333, 2013 [ABSTRACT FROM AUTHOR]

A systematic study of 15 neutron-irradiated blue topaz samples was conducted using high-purity germanium (HPGe) digital gamma-ray spectroscopy. The specific activity of the detected radionuclides (134Cs, 182Ta, 46Sc, and/or 160Tb) was measured, and the decay pattern of the irradiated topaz was determined. Based on the time elapsed since their removal from the nuclear reactor, the amount of time required for the residual radioactivity to decay to safe levels was calculated. Most of the samples were safe at the time of the first measurement (95 days after irradiation), but higher concentrations of radionuclide impurities in some samples will require them to be quarantined for several years. [ABSTRACT FROM AUTHOR]

The article presents abstracts on instruments and techniques in gemology which include the application and development of digital image processing in gemmology, the use of cameras and computers in photographing jewelry and the use of digital combination photography in improving images of microscopic minerals.

The article presents abstracts on gems which include a description of the three sources of high-quality aquamarine from Minas Gerais, Brazil, an analysis of the chemical composition of nephrites from China and a comparison of mechanical mining and traditional mining in Sri Lanka.

The article presents abstracts on synthetic and simulant gems which include a description of bead materials, a discussion of gemmological characteristics and identification of a kind of dyed red coral imitation and a discussion of polymerization recycling of wasted turquoise.

The article presents abstracts on gemstones which include the determination and distribution characteristics of trace rare earth elements in pearls using inductively coupled plasma mass spectrometry (ICP-MS), assessment of granitic pegmatites and a description of pearls from the lion's paw scallop.

The article focuses on a test conducted to 21 samples of black-and-white diamond jewelry using Fourier transform infrared (FTIR) and Raman spectroscopy. It is said that about 10 of the jewelry samples were found to have black synthetic moissanite. Raman spectroscopy revealed that the inclusions in black synthetic moissanite were determined as crystalline silicon. The research "Synthetic Moissanite: A New Diamond Institute" by K. Nassau et al. noted that such moissanites were not developed through a so-called seeded sublimation process.

The article presents abstracts on jewelry history which include a description of the characters of gemstones from Liangzhuang King's tomb in Ming Dynasty in Zhongxiang, Hubei Province, China and an exploration of Western lapidary tradition in geological literature.

The article presents abstracts on gem-related treatments which include the filling of fractured rubies with glass-forming additives, identification of treated chicken-blood stones and imitations and a description of three dimensional fluorescence spectra representation of natural and treated amber.

An abstract of the article "Pt Alloy Materials for Jewelry and Ornaments," by Y. Ning is presented.

The components and evolution of subcontinental lithospheric mantle beneath the North China Craton and the Yangtze Craton is a current topic in the geological study of China and the carbon isotopic composition of diamond is one of the most direct probes into cratonic lithospheric mantle processes. In this paper, in-situ SIMS (Secondary Ion Mass Spectrometry) techniques were used to analyze the carbon isotope compositions at different internal growth zones of diamonds from Shandong and Liaoning in the North China Craton and Hunan in the Yangtze Craton. It was found that the carbon isotopic range of diamonds from the North China Craton are rather distinct from those of the Yangtze Craton; the former has a range of −6.0/‰ to −2.0‰ (relative to VPDB) with an average value of −3.0‰ in their core areas, which is consistent with global peridotitic diamonds; the diamonds from the Yangtze Craton, however, have a carbon isotopic range from −8.6‰ to −3.0‰ with an average value of −7.4‰ in their core areas, being more consistent with global eclogitic diamonds. The variations of carbon isotope ratios between different internal growth zones in individual diamonds were different in the three diamond localities studied. There was a clear correlation between changes in carbon isotopic composition and phases of diamond dissolution and new growth, while no correlation was observed between δC and internal inclusions. The variations suggest that the carbon isotopic compositions of mantle fluids were changing during the process of diamond crystallization, and that the heterogeneity of the carbon isotopic composition in mantle carbon reservoirs was a more important factor than carbon isotope fractionation in controlling the carbon isotopic compositions and their variation in diamonds. In addition, the preliminary results of in-situ nitrogen analyses demonstrated that the variation of carbon isotopic compositions between the core and outer growth zones does not correlate with nitrogen abundances, implying either that diamonds crystallized in an open environment or that the carbon isotopic composition and nitrogen contents in mantle fluids were controlled by other, not yet understood factors. The experimental results provide hints that the isotopic composition of carbon and its original sources were different in metasomatic fluids controlling diamond formation in the mantle beneath the North China Craton and the Yangtze Craton. [ABSTRACT FROM AUTHOR]

The combustion characteristics of municipal sewage sludge samples with five different initial water contents (5.02, 8.21, 17.33, 27.45 and 37.85%) were assessed by using a thermogravimetric analysis approach. The ignition temperatures of the samples increased with increasing the heating rates and their initial moisture content. Ignition, burnout and comprehensive performance indices of the samples increased with decreasing their initial moisture contents. Between heating rates of 20 and 80 K min, the average ignition, burnout and comprehensive performance indices of the sample with initial moisture content of 5.02% were about 1.2, 2.2 and 0.9 times more than those of the sample with initial moisture content of 37.85%. The average activation energies for the samples with 5.02, 8.21, 17.33, 27.45 and 37.85% moisture contents were 146.59, 148.02, 155.13, 156.70 and 168.39 kJ mol. There were certain linear relations among two main kinetic parameters for the samples with different moisture contents and their main combustion stages. [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]

The article presents abstracts on gems which include a description of a valuation model for cut diamonds, presentation of a dataset for conflict diamonds and a study on disease status of gem worker's silicosis.

The article presents abstracts on topics about gems which include the application of geochemical ratios for delineating gem-bearing sites, the distribution of microelements in Pinctada martensii and its manual nucleus inserted pearl layer, and the impact of supergene conditions on fossil ivory quality.