Synthetic Gems Research Articles

Why Are Some Crystals Gem Quality? Crystal Growth Considerations On the “Gem Factor”

Abstract The purpose of this work is to investigate the crystal growth parameters necessary or sufficient to obtain a crystal specifically of gem quality. We assume adequate chemistry is available. First, nucleation must occur with only a limited number of nuclei, otherwise too many crystals will be produced, and they will be too small to be faceted into a gem. Two growth mechanisms are readily documented for gems: Most commonly there is slow growth, driven by a spiral growth mechanism, leading to large single individuals. There are only a few examples of fast growth leading to gem-quality edifices: examples include “gota de aceite” Colombian emerald or the dendritic “pseudo cube” for gem diamonds. We have not documented the intermediate conditions between these two extremes in the Sunagawa diagram, which would correspond to 2D nucleation growth. The presence of inclusions is to be limited to desirable ones. Thus, in general, a good stability of the growth interface is the best guarantee of good clarity in the final gem. As for the interface, in general, growth conditions must be relatively stable over the period necessary to achieve growth. Perhaps surprisingly, it has become well documented that gem-quality near-colorless diamonds may have experienced quite a complex growth history. Therefore, the term stability has to be re-defined for each system producing a given gem. The length of time it takes to achieve crystallization of the gem has rarely been studied or estimated. Scientific evidence from experimental petrology and the growth of synthetic gems indicates that it does not take millions of years to grow a gem, but that this exercise may be achieved in a week to, arguably, a few years at the most. Available free space to grow does not appear always necessary, but it helps. Otherwise deformation, inclusions, and other negative effects may occur. Finally, no dramatic post-growth events, such as fracturing or etching, should affect the gem crystal.

Synthesizing precious gems

The international gem trade can be a shady business. In a quiet corner of a busy London pub, a trader, who asked to remain anonymous, tells C&EN about passing off synthetic gems, made in a manufacturing plant, as natural. “This is worth more than $500,000,” the trader says, flashing a hand upward to reveal a gold ring clasping an emerald the size of a sugar cube. “Well it would be, depending on whether you consider it real or fake.” The trader admits to buying synthetic gems—which can be 30–40% cheaper to produce than natural gems—and then selling them to jewelers as natural. The trader is unwilling to discuss specific deals, as this could bring some heat from previous customers. Scientists have been able to make synthetic diamonds and other precious gems for decades, but in the past couple of years, technologies such as the one used to make the London

The ecology of diamond sourcing: from mined to synthetic gems as a sustainable transition

Luxury goods such as gemstones constitute a challenge for moving towards a sustainable society. From a purely bio-economic perspective, such goods consume planetary resources to provide a human “want” rather than a “need”. However, their extraction or manufacturing also provides important livelihoods for communities along the supply chain and hence contribute towards development outcomes. Comparing mined versus synthetic gems can provide consumers with important benchmarks on choice. The energy usage and emissions in mined versus lab-created diamonds was evaluated, based on industrial data, since these two factors are often a general indicator of environmental impact that can be useful in product comparisons. Depending on the process and the location of the mine, the data can be highly divergent and cannot be used as a singular measure of environmental impact. There is a need to develop life cycle analysis techniques from industrial ecology to conduct a detailed comparison of synthetic versus mined stones. Informed consumers could help to transition this luxury good towards a mix of mined and synthetic gems that best meet ecological and social metrics of sustainability.

Synthesis and Characterization of Colorant Glass and Glass Ceramic from Non Stoichiometric Cordierite Composition with the Addition of Colorant Material at Different Temperature

Cordierite glass of non stoichiometric (2.8MgO 1.5Al2O3 5SiO2) can be used to synthesis the synthetic gems because of it properties. The colorant glaze material; 2% , which from trace element cam give colorant to cordierite glass sample. The XRD analysis give result that α-cordierite formed at temperature 1250°C. The density and porosity of cordierite glass decreased as the sintering temperature increased. The hardness from Vickers Hardness are increased as the sintering temperature incerased.

Large Colorless HPHT-Grown Synthetic Gem Diamonds from New Diamond Technology, Russia

Large Colorless HPHT-Grown Synthetic Gem Diamonds from New Diamond Technology, Russia

AVASPEC 2048: an innovative spectroscopic methodology to differentiate the natural emeralds from the synthetic ones

New and sophisticated synthetic gems are constantly introduced in the market making the identification of them very difficult, if one uses only the microscope. In this paper we present the results obtained from a new methodology, the AvaSpec-2048 spectrometer, that can help to identify the natural emeralds from the synthetic ones. The AvaSpec-2048 spectrometer is an original instrument that can acquire electromagnetic spectra in a range between 400 nm and 1000 nm (VIS-NIR), and can be used to identify gemological materials allowing an accurate discrimination of natural products from the artificial ones. The physical and optical properties, microscopic features and absorption spectra of natural and synthetic emeralds have been also investigated through others traditional methodologies such as optical analysis, specific gravities, refractive indices and Vis-NIR spectroscopy. The comparison of the absorption spectra obtained with the AvaSpec-248 spectrometer allows identifying and distinguishing the origin of the analyzed gems.

Update on Gemstone Mining in Luc Yen, Vietnam

In 1987, gems were discovered in the Luc Yen area of Vietnam's Yen Bai province. Ruby, sapphire, and spinel from primary and secondary deposits are the most valuable of these; tourmaline, gem-quality feldspar, pargasite, and humite are also mined there. As a result of this discovery, the Luc Yen district has become Vietnam's most important gemstone-trading center over the past 30 years. The markets of Yen The, the capital of Luc Yen, offer an additional assortment of natural gems from Vietnam and elsewhere (including peridot, beryl, aquamarine, topaz, and quartz); synthetic gems are also found in these markets.

Characterization of a Synthetic Nano-Polycrystalline Diamond Gemstone

A potential new synthetic gem material in the form of a faceted 0.88 ct brownish yellow nano-polycrystalline diamond (NPD) has undergone a full gemological examination, including detailed spectroscopic analysis, for the first time.

Sensitivity study of ozone retrieval from UV measurements on geostationary platforms

This paper addresses several aspects related to ultraviolet (UV) measurements from an upcoming geostationary orbit (GEO) satellite mission. First, using simulated cloud coverage based on the MTSAT (Multi-functional Transport Satellite 1R) 650nm channel as a proxy, we find that GEO observations can increase clear-sky coverage by ~4 times. Secondly, we examine the feasibility of improved ozone detection with GEO observations, using synthetic GEMS spectra with GEO geometries along with the TOMS total ozone algorithm and an ozone profile algorithm based on the optimal estimation method. The sensitivity of ozone retrievals to the lower troposphere is limited at large solar and satellite zenith angles, especially above 70° under clear-sky conditions. Third, we evaluate two new ideas for improving ozone retrieval sensitivity in the troposphere at large angle geometries; (1) a geosynchronous orbit with an inclination-angle of 30°, with smaller values of viewing zenith angles than those from a geostationary orbit; (2) a combination of UV measurements at multiple solar zenith angles to improve the accuracy of ozone profile retrievals.

Study of Natural and Synthetic Quartz by Raman Spectra

The FWHM of Raman spectrum, which is the life-span of phonon, can provide valuable information of natural or synthetic gem. Through testing the natural and synthetic quartz by BTR111-785 mini-Raman spectroscopy, it is found that the FWHM of natural quartz is more than 30 cm-1, withal the FWHM of synthetic quartz is less than 30 cm-1.

Synthetic Gem Materials in the 2000s: A Decade in Review

Synthetic Gem Materials in the 2000s: A Decade in Review

Applications of Raman spectroscopy to gemology

Being nondestructive and requiring short measurement times, a low amount of material, and no sample preparation, Raman spectroscopy is used for routine investigation in the study of gemstone inclusions and treatments and for the characterization of mounted gems. In this work, a review of the use of laboratory Raman and micro-Raman spectrometers and of portable Raman systems in the gemology field is given, focusing on gem identification and on the evaluation of the composition, provenance, and genesis of gems. Many examples are shown of the use of Raman spectroscopy as a tool for the identification of imitations, synthetic gems, and enhancement treatments in natural gemstones. Some recent developments are described, with particular attention being given to the semiprecious stone jade and to two important organic materials used in jewelry, i.e., pearls and corals.

Seeking Low-Cost Perfection: Synthetic Gems

Synthetic gems are superlative examples of crystal growth. Today, industrial and scientific crystal growth is a highly sophisticated endeavor employing a wide range of methods. Many of these have been adapted to grow gems for jewelry use. Most major gemstones have been synthesized, and these products are commercially available around the world, often at a fraction of the cost of a natural gem of comparable size and quality. Distinguishing them from their natural equivalents involves a number of interesting challenges. Inclusions (internal features) observed by microscopy often provide conclusive proof of synthetic origin. When routine testing procedures (refractive index, specific gravity, fluorescence, and internal inclusions) do not provide sufficient evidence, laboratories must employ more advanced analytical instrumentation.

E.J. Gübelin and J.J. Koivula Photoatlas of Inclusions in Gemstones. Opinio Publishers, Basel, Switzerland. 2008, 3, 672 pp. including 1796 colour images. Price €250 (Hardback), ISBN: 3-03999-047-4.

Photoaltlas, volume III, like its predecessors, volumes I and II, provides a stunning, visual record with accompanying descriptions of a wide variety of mineral and fluid inclusions in gems. The atlases are designed primarily for gemmologists and jewellers as an aid to the recognition of treated and synthetic (manufactured) gems and the characterization, and possible provenance, of gem materials. Good quality gloss paper is used throughout to provide high colour photomicrographs of exceptional quality. The `pay-back' is that, at just over 2.5 kg, the present atlas is somewhat unwieldy and, at €250, rather expensive. Volume III is organized into three sections. Section I (12 pages) comprises a Preface, a Foreword, Acknowledgements and a brief Introduction and Notes on how to use the …

A Study of Nail-Head Spicule Inclusions in Natural Gemstones

material requires testing with a variety of instruments, in most cases the stone’s natural or synthetic origin can be determined conclusively by features seen with magnification. For example, curved lines/bands (flame fusion), “hounds tooth” patterns (hydrothermal), and “wispy veil” inclusions (flux) are all classically associated with synthetics. Nail-head spicules are typically associated with synthetic hydrothermal (and occasionally fluxgrown) emerald (figure 1) and synthetic quartz (figure 2). However, such inclusions have been reported in a number of natural and other synthetic gem materials (table 1), including natural emerald (DelRe, 1992; Rockwell, 2003). Similar-appearing features have been observed in photomicrographs of natural sapphires from Madagascar (Kiefert et al., 1996; Milisenda and Henn, 1996), though they have not been described in detail. This article documents nail-head spicules and similar-appearing features in a variety of natural gem materials, which could potentially lead to their misidentification as synthetics.

特別講演(1) 天然、処理及び合成ダイヤモンドの鑑別

特別講演(1) 天然、処理及び合成ダイヤモンドの鑑別

The detection of colour-enhanced and synthetic gem diamonds by optical spectroscopy

In this article, the spectroscopic methods used to assess gem-quality diamonds are reviewed. From such measurements it is possible to determine, in the majority of cases, whether the colour of a stone is natural, or has been changed by some form of treatment—either HPHT processing, radiation damage and annealing, or a combination of both methods. Methods used to identify synthetic diamonds are also covered briefly.

Study on inclusions in natural and synthetic gems

The characteristics of inclusions in natural and synthetic gems are distinct owing to their different forming mechanisms and can be utilized to distinguish gems from different localities. In addition, intensive studies on inclusion characteristics of natural gems could identify their geographical origins and provide valuable information on gem synthesis. In this paper synthetic gems (synthetic star-spangled sapphire and emerald) and natural gems from various locations including natural sapphire from Thailand and Australia, and natural aquamerine from Mufushan, Hunan Province, and Ailaoshan, Yunnan Province, were selected for the comparative study of inclusions. Significant research results have been achieved, thus providing the important basis for distinguishing natural from synthetic gems.

Oleg Tsarev's Synthetic KGB Gems

The Crown Jewels, published in Great Britain in 1998 and the United States in 1999, is Oleg Tsarev's second book drawn from KGB archives and written in cooperation with a Western author in this case, Nigel West.1 This important, complex book has much to offer historians, especially those inclined toward archeology, for Tsarev has skillfully choreographed his version of history to dance around the facts of some very well known intelligence and espionage cases. Consequently, he deposits another dense layer of evidence to sift, sort, and evaluate. But an assessment of Tsarev's volume also leads to three major points. Admittedly, two are glimpses of the blindingly obvious,'' restated here because these fundamentals become buried under media hype. First, that new historical evidence requires careful interpretation. Second, the secrets spies gather should be evaluated within the context of national and institutional policy formulation and implementation. Third, the notion of damage'' from Soviet espionage, has been exaggerated and misunderstood, and it is now time to investigate the impact of Soviet espionage upon national and international politics. And, most relevantly, Tsarev, a former lieutenant colonel in the Russian Foreign Intelligence Service, also serves as a consultant to the Service's press department.

Moissanite - Black Diamond- Challenges for Gemologists in the Third Millennium?

Almost four years ago a new synthetic moissanite was on show at the exhibition in Tuscon, Arizona. Because of its physical properties, e.g. hardness 9.25 on the Mohs scale, the moissanite became a big challenge for gemmologists. Its thermal properties are very similar to the thermal properties of diamond. That is why the classic diamond tests are almost useless when trying to determine wheter a sample is the diamond or synthetic moissanite. Besides, informations on the new synthesis are still mainly unavaliable for the public. The so called black diamond was examined. Even though the certificate which accompanied the stone assured the origin of two heavier »black diamonds« from the same knee we proved that the sample is a synthetic moissanite rather than the black diamond. If the production of synthetic gems similar to the natural gems was the major challenge for gemologists in the last decades of this Millennium - what will be in the next?