gems, jade, fei cui, pyroxene jade, Guatemala, jadeite, omphcite

At the AGTA show, the author spoke with Brent Smith, owner of Phoenix Gems (Holly, Michigan), who presented several parcels of rough spinel in various colors recently mined in Malawi. Although spinel occurrences were identified in 2014, actual mining operations only began in 2024 and are now producing moderate quantities, though exact figures remain unavailable. The rough stones ranged from 4 ct to over 10 ct. Some parcels featured pink spinel with tones from light to medium-dark and saturations up to moderately strong; these stones were translucent to transparent, relatively clean, and fluoresced bright red under UV light. Other lots included spinel in hues from bluish gray to grayish blue to violet-blue, with tones from medium-light to dark and no UV fluorescence; these stones were highly transparent and lacked eye-visible inclusions. Smith also reported encountering dark purple spinel from the same source. The material was reportedly mined in Makoko, a village in southern Malawi, where early finds were small and of poor quality until recent operations uncovered gem-quality crystals. According to Smith and other gem dealers familiar with the area, no gem-quality Malawian spinel had previously been known in the trade. Phoenix Gems was the only exhibitor offering this new material at the show. As Malawi continues to develop its gem resources, ethical trade practices remain a priority. Smith explained that Phoenix Gems collaborates with the Export Development Fund (EDF), a subsidiary of the Reserve Bank of Malawi, to ensure fair payment to local miners through an official selling channel. EDF is also working to introduce Malawian spinel to international markets. This cooperative effort between local institutions and international dealers signals a positive step toward a more transparent and sustainable gemstone supply chain in Malawi.

gems, corundum, Burma.12, Madagascar, inclusions

Extensive research has been conducted on sapphires, yet methods for identifying the provenance of pink-purple sapphires, particularly those from Vietnam and Madagascar, remain limited. This study examined samples from both locations using gemological tests, microscopic observations, and various spectroscopic techniques, comparing them with pink-red corundum from other sources. Vietnamese samples exhibit a foggy appearance with orange iridescence, while Madagascan samples have a stronger purple hue. Color analysis attributes the pink hue to Cr³⁺ absorption peaks, with Madagascan samples showing enhanced blue light transmission due to Fe³⁺ and Fe²⁺–Ti⁴⁺ transitions, leading to a purple tint. Inclusions further distinguish their origins: Vietnamese sapphires contain white and blue bands, cloudy inclusions, and calcite and apatite deposits indicative of marble-type origins, while Madagascan samples, rich in small zircon formations and clusters, originate from alkaline basalt. Chemical analysis confirmed these findings, showing Vietnamese samples have lower V, Mg, and Ga but higher Fe compared to marble-type pink-red corundum from Myanmar and Yunnan, China, whereas Madagascan samples have lower Fe and higher Ga than high-iron pink-red corundum from Thailand, Cambodia, and Tanzania. This study holds significant value in tracing and identifying the origins of pink-purple sapphires.

gems, beryl, emerald, gemology, origin determination, Colombia, Brazil, Zambia, Russia, Afghanistan, Pakistan, China, Zimbabwe

Emerald is a precious colored gemstone, and its origin has a significant impact on the evaluation of its value. The identification of the origin of emerald has become an important technology in gemstone laboratories and a research hotspot in the field of gemology. The inclusion, spectral characteristics, and chemical composition of emerald are commonly used and critical information for origin determination. However, with the accumulation of research data on the origin of emerald, traditional methods for origin determination are facing challenges. This article systematically summarizes and analyzes the gemological characteristics, inclusion information, spectral features, and major and trace element data of emeralds from various occurrences around the world. Based on a review of previous research results, it systematically elucidates the current research status of emerald origin determination, summarizes the gemological characteristics and inclusion characteristics, reveals the component fingerprint of emeralds from each occurrence, and uses case studies to illustrate the methods of distinguishing common and important origins of emeralds. Although the comparison at a global scale indicates that the inclusion varieties of emerald from different origins are mostly similar, with spectral convergence and significant overlap in component content ranges, novel approaches for origin determination are proposed based on inclusion frequency, UV–VIS–NIR spectral patterns, absorption patterns of HDO and D₂O, and the parameter selection of compositional diagrams.

gems, inclusions, beryl, emerald, ruby, sapphire, diamond

Self-published book on inclusions in gems.

gems, corundum, treatments.6, low-temperature heat enhancement, Mong Hsu ruby, diaspore

This study examined the effects of low-temperature heat treatment on the characteristics of rubies from Mong Hsu, Myanmar. Five ruby samples were heated to 400, 600, 900, and 1200 °C for varying durations. Before and after each heating step, visual examinations were conducted using a gem microscope under different illumination conditions. Various spectral techniques—UV-Vis, FTIR, Raman, and photoluminescence (PL)—were employed to assess the changes induced by heating. The treatment enhanced the rubies by partially or completely fading the dark blue core, which in turn increased overall light transmittance and enhanced the fluorescence peak around 694 nm, though it did not improve the red hue of the samples. Two primary effects were observed. First, the fading of the dark blue core with increasing temperature was attributed to changes in the intervalence charge transfer (IVCT) between Fe²⁺ and Ti⁴⁺. This IVCT variation was negligible below 900 °C but became pronounced at 1200 °C. Second, a shift in the FTIR spectrum, particularly the 630 cm⁻¹ peak, was observed and is thought to result from the decomposition of mineral inclusions during heating. This FTIR peak proved to be sensitive to low-temperature heat treatment and may serve as a useful indicator for detecting such treatment in Mong Hsu rubies.

gems, spinel, spinel chemistry, spinel nomenclature, spinel color, cobalt-blue spinel

Cobalt-blue spinel from two localities (Qila and Trailside) on Baffin Island, Nunavut, Canada, are compared with other spinels from 12 occurrences in the same geological terrane and to Co-bearing blue spinel from other localities worldwide. Qila spinel is suitable for cutting cabochons, which commonly incorporate small amounts of associated calcite, dolomite, corundum, fluorapatite, pargasite and other silicates, as well as secondary cobaltpentlandite and fluid inclusions. Trailside spinel can be faceted into small gemstones (generally <0.2 ct), which rarely contain magnesite, fluorapatite, muscovite and CO2-rich fluid inclusions. The bright blue colour of the spinels from Qila and Trailside is due to TCo2+, although they also contain other chromophoric elements such as Fe and traces of Cr, Mn and V. Compared with other Mg-Al spinels from Baffin Island, those from Qila and Trailside are generally enriched in Co, Ni, Mn, Li and Be, and depleted in Ti, V and Cr. In addition, the Qila and Trailside Co-blue spinels are fairly chemically distinct from those of other world localities: they are depleted in V and Ti, fairly poor in Cr and Zn, and considerably enriched in Co and Mn. A new approach for the preliminary chemical discrimination of gem spinels is proposed by plotting the weighted chromophore concentrations in a ternary diagram (i.e. Cr+V vs 40×Co vs Fe/8). These weighted percentage values are also plotted against the ppmw concentrations of the chromophoric elements in X–Y plots, which provide further correlations of high Co with vivid Co-blue spinel and elevated Fe with overly dark non-gem spinel. This method can be applied to samples that are difficult or inefficient to characterise using spectroscopy, such as spinel grains in heavy-mineral concentrates obtained during regional exploration programmes.

gems, corundum, color.4, treatments.6

Evidence of heat treatment of gem corundum can be provided by microscopic observations (e.g. altered inclusions), blue luminescence to short-wave UV excitation (254 nm), and FTIR spectroscopic features. For metamorphic-type stones, evidence of heating is provided by the presence of a low-intensity infrared absorption band at 3232 cm⁻¹, and sometimes by another band at 3185 cm⁻¹, that accompany a band at 3309 cm⁻¹ (therefore known as the ‘3309 series’; Hughes & Emmett 2005; Beran & Rossman 2006; Saeseaw et al. 2020). Recently, a similar feature at 3234 cm⁻¹—also accompanying the 3309 cm⁻¹ band, but with two additional bands at about 3380 and 3395 cm⁻¹—was reported for a blue sapphire which, because it contained diaspore inclusions, presumably could not have been heated to more than 550 °C (Krzemnicki et al. 2023). In the present note, we document for the first time a heated sapphire with FTIR bands at 3234, 3380, and 3395 cm⁻¹ occurring together with the 3309 cm⁻¹ band.

gems, jade, pyroxene jade, jadeite, omphacite, kosmochlor, geology, supercritical geofluid, genesis of jadeite jade, subduction zone, high field strength elements, fluid-melt inclusion

Supercritical geofluids are transitional fluids formed in silicate rock–H₂O systems under conditions of high temperature and pressure. Their chemical compositions lie between those of aqueous fluids and magmatic melts. Possessing strong capacities for dissolution, transport and reaction, they serve as important carriers and media for material circulation within the Earth. Traditional models for the origin of primary jadeite jade (jadeitite)—including regional metamorphic, magmatic and metasomatic theories—are supported by evidence from experimental petrology, petrography and petrogenesis. However, each encounters difficulties in explaining mineral crystallization sequences, mineral assemblages and their spatial distributions. The original fluid-precipitation and metasomatic-replacement theory proposes two modes for the formation of the constituent minerals of jadeite jade. Commonly observed fluid–melt inclusions within jadeite and omphacite grains and their aggregates indicate that primary jadeitites crystallized from fluid–melt miscible systems. Drawing upon advances in the study of supercritical geofluids in Earth sciences and recent research on jadeite jade, this paper presents a supercritical-geofluid model for jadeitite formation. In this model, supercritical geofluids generated by dehydration of the subducting slab transport dissolved materials under suitable pressure–temperature conditions. Changes in temperature, pressure and related parameters lead to the crystallization and infilling of early jadeitite within fractures and fissures of the mantle wedge, followed by superimposed metasomatism. This model is supported by multiple lines of evidence, including characteristic fluid–melt inclusions, pronounced dissolution relics, early infilling textures, middle- to late-stage metasomatic textures, enrichment in high-field-strength elements, abundant and complex mineral (or solid-phase) assemblages, and high- to ultra-high-pressure veins containing diagnostic minerals. Chromite, a magmatic mineral predating the formation of early jadeitite, was subsequently dissolved or replaced, providing the Cr³⁺ responsible for the green coloration of jadeite jade. Following its initial formation, jadeitite underwent multiple geological processes, including melt activity and fluid activity (both crystallization and metasomatism) associated with the separation of supercritical geofluids, as well as deformation, metamorphism and supergene alteration. To establish a comprehensive theoretical framework for jadeite jade formation, further investigation and reassessment are required, with particular attention to the timing and role of supercritical geofluid activity.

gems, beryl, emerald, tourmaline, schist-hosted, Zambia, Russia, Pakistan, Ethiopia

A 3.80 ct emerald containing well-formed black, opaque prismatic crystals was examined. Raman spectroscopy identified the surface-reaching crystals as tourmaline, an uncommon inclusion in emeralds that has been documented in schist-hosted deposits in Zambia, Pakistan, Russia, and Ethiopia. Laser ablation–inductively coupled plasma–mass spectrometry chemical analysis, combined with inclusion observation, revealed the emerald to be of Zambian origin.

gems, jade, pyroxene jade, jadeite, fei cui, omphacite, kosmochlor, Guatemala

In recent years, a new kind of Guatemalan jade has entered the Chinese jewelry market, where it is called yongchuliao fei cui (or yongchuliao for short). Prior to the availability of yongchuliao, Chinese consumers had a negative impression of Guatemalan material and preferred Burmese jade. However, the recent emergence of this new high-quality blackish green jade has attracted the attention of Chinese buyers. The authors recently tested a rough stone and a carved pendant of yongchuliao. Under reflected light, these samples appeared blackish green with a greasy luster similar to Burmese inky black jade. The rough stone was opaque and had numerous fine white inclusions measuring approximately 300 μm in diameter on its surface. The carved sample was bright green with coarse texture and medium transparency under transmitted light. The rough and carved samples had a refractive index of 1.67 and specific gravities of 3.342 and 3.332, respectively. These gemological characteristics are consistent with both jadeite-type jade and omphacite-type jade. Qualitative analysis using energy-dispersive X-ray fluorescence spectrometry revealed magnesium, aluminum, silicon, calcium, chromium, manganese, and iron, among other elements. It should be noted that the ideal chemical formula of jadeite is NaAlSi₂O₆ and that of omphacite is (Ca,Na)(Mg,Fe,Al)Si₂O₆. Jadeite and omphacite can form a complete solid solution. The occurrence of calcium, magnesium, and other elements implies that the mineral composition of yongchuliao is not pure jadeite. Raman shifts at 681, 514, 411, 378, 340, and 209 cm⁻¹ were consistent with those of omphacite. The Raman spectra of fibrous inclusions in the carved sample also matched those of omphacite rather than jadeite. The strongest Raman shift at 681 cm⁻¹ was attributed to the symmetrical Si-O-Si stretching vibration. Raman spectroscopy was used to compare the samples’ mineral composition against the RRUFF database, revealing that yongchuliao material consists almost entirely of omphacite. The fine white inclusions distributed evenly in the rough sample were coincident with titanite. In addition, some of the sample was ground into powder for X-ray diffraction analysis to obtain the mineral composition of the whole rock. The results showed an omphacite content of about 98.49% (with a 5% margin of error), and the rest was magnesian calcite. The results from Fourier-transform infrared absorption spectroscopy were consistent with the Raman spectra, identifying the main mineral composition of the samples as omphacite. A double-sided polished piece was cut from the rough sample for testing. Its ultraviolet/visible/near-infrared (UV-Vis-NIR) absorption spectrum showed an absorption peak at 437 nm, indicating the presence of Fe³⁺. Absorption peaks at 637, 657, and 688 nm were also observed and attributed to Cr³⁺. Based on testing, both samples were omphacite-type jade containing titanite inclusions. Since almost all of the yongchuliao we have observed exhibited nearly the same colors and textures as these samples, it is likely that other yongchuliao may also have similar mineral compositions.