ciando.com

Alexandrite, a variety of chrysoberyl, and one of the finest colour-change natural gemstones, may almost be called “the national gemstone of Russia”. This great prestige is based on two facts: its noble name in honour of the Tsarevich Alexander Nikolaevich (the future Tsar Alexander II) and its dazzling colours, green in daylight and red in incandescent light, the military colours of Imperial Russia. Although quantities of facetable quality alexandrite are considerably less than those of emerald, alexandrite is counted among and compared to the “big four” of the gem business: diamond – ruby – sapphire – emerald.

In this book the authors present an historical overview of emerald mining in the Urals, the discovery of Russian alexandrites in the Uralian emerald mines, the naming and historical use of alexandrites and their appearance and display in mineralogical museums and the gem trade. Morphology and twinning of rough alexandrite is described for single crystals, single contact twins and cyclic twins (trillings). Mineralogical and gemmological properties are thoroughly explained and numerous photo-micrographs of inclusions and growth patterns in faceted samples are presented.

Chatoyancy and asterism of alexandrite and chrysoberyl from Russia and Sri Lanka are also described. A further chapter deals with characteristic growth patterns of Russian, other natural and synthetic alexandrites. Colorimetric data of Russian alexandrites and green chrysoberyls are explained using the CIELAB colour space, and the distinction between these varieties is explained. A chapter on trace element chemistry and locality determination rounds off the book.

An extensive appendix containing lists of historical names, a time table and numerous references provides valuable information on Russian alexandrites for all researchers in the mineralogical and gemmological fields as well as for gemmological laboratories, jewellers and gem dealers.

Consequently, this book, illustrated with more than 200 colour figures and photographs, addresses mineralogists, gemmologists, historians, mineral and gem collectors as well as all members of the gem trade.

This book is lavishly illustrated with photographs, tables and crystal diagrams; many of which are attributed to the principal author. Among these are particularly attractive photographs of emerald and alexandrite crystal groups that clearly emphasise important details. Chapters 5, 7 and 8 contain many crystal diagrams that depict different faces in different colours; these are especially useful for a clear understanding of crystal orientation and twinning patterns and all are the work of the principal author. The historical descriptions are enhanced by numerous photographs and copies of portraits.

Chapter 1 provides a short overview of the history of the discovery of Uralian emeralds in 1830 and the mining activity, albeit intermittent, that followed. Associated with the emeralds was alexandrite, a rare colour-change chrysoberyl that was only recognised in 1833. In 2007, the principal author and LK were among a party of scientists permitted to visit the underground workings of the Malysheva Mine.

Chapter 2 briefly describes the history of the discovery, development and exploitation of the various Uralian emerald deposits from the chance discovery of the first emerald in 1830 to the preliminary closure of the last operating mine in 2007.

The longest chapter in the book, Chapter 3, details the discovery, naming and early history of Russian alexandrite. The story of alexandrite is closely linked to the Russian Imperial Family and to the many bureaucrats involved in both the mining and the Ekaterinburg cutting factory. Immediately following the discovery of alexandrite, academic contributions were made by several leading scientists and mineralogists of the time including Gustav Rose, Nils von Nordenskiöld, David Brewster and Jöns Berzelius. A timetable of events on page 132 details the complex history of this period. This chapter also discusses the, often misquoted in literature, timing of the discovery, identification and naming of alexandrite in honour of the Tsarevich Alexander Nikolaevich.

The next three chapters discuss the morphology and twinning of alexandrite crystals together with their mineralogical and gemmological properties.

Chapter 4 describes the trials and tribulations of assimilating a suitable collection of rough and cut Russian alexandrite. The lengthy list of acknowledgements demonstrates the size and complexity of this project; samples of alexandrite used for comparative work had to be from known sources, often difficult to prove with historically mined material. Many photographs of Russian alexandrite specimens and emerald crystal groups housed in Museum collections are included and some have been verified and matched to those described from the 19th century.

Chapter 5 describes in detail the morphology and twinning of single alexandrite crystals and trillings utilizing clear diagrams that depict different faces in different colours and numerous photographs.

Chapter 6 describes the mineralogy of Russian alexandrite Raman microprobe and SEM-EDX work was applied to confirm the matrix minerals of alexandrite crystal groups as phlogopite, margarite and plagioclase. EDXRF X-ray fluorescence showed Ti, Fe, Ga, V and Cr as trace elements. Detailed growth features were studied and photographed using immersion microscopic techniques whilst Raman spectroscopy was applied to identify phlogopite, fluorite and apatite as inclusions within the alexandrite.

Chatoyant and asteriated chrysoberyl and alexandrite are briefly described in Chapter 7.

Chapter 8 discusses the common growth habits of Russian chrysoberyl, comparing them with synthetic crystals and specimens from India, and Sri Lanka. Growth habits, seen as geometric zoning by immersion microscopy, are compared with crystal morphology.

Chapter 9 covers colorimetry and the application of CIELAB colour space. This work details colour analyses for colour change effects and pleochroism making reference to trace element chemistry from LA-ICP-MS and comparison with specimens from other sources. The designation of non colour-change chrysoberyl is also discussed.

The final chapter presents the results of trace element chemistry by LA-ICP-MS. Comparison is made using alexandrite from Tanzania, Brazil, Sri Lanka, India and Russia and several key points are given for identifying the provenance of Russian material.

The Appendix contains seven tables, a transcription of names, an historical timetable, an extensive list of references and an index.

This is an attractively produced book with subtle colour changes of green and purple print on the pages and chapter headings that reflect the colour-change properties of alexandrite.

This well researched and detailed collaborative work provides valuable information to all those who have an interest in gems and gemmology.

Review by Susan and Vernon Stocklmayer published in The Australian Gemmologist, July-September 2010, Volume 24, Number 3, page 73.

Unusual Crystal Shape

Alexandrite is a variety of the mineral chrysoberyl having the chemical composition beryllium aluminate, where as the emerald is a beryllium aluminium silicate. Both are coloured by chromium element. Chrysoberyl and its varieties like cymophane and alexandrite crystallize in the orthorhombic system and exhibit an unusual and characteristic crystal form called cyclic twin. Cyclic twin one has to see to appreciate the growth of the radial arrangement of the twin members that they look almost like flowers.

The Natural History Museum in London hosts two large twin crystals of Russian alexandrite sizes approximately 3.5x4.5cm and 6.5x6.5cm. Schmetzer has given a detailed account of the morphology and twinning in Russian Alexandrite with superb artwork in colour explaining how these unique cyclic twins with and without re-entrant angles have developed. It is for the first time that such detailed explanations have been given for every twin, interpenetrated twin, cyclic twin and intricacy involved in their growth making the treatise very valuable.

Gemmological Properties

If one compares the properties of alexandrite with those of emerald, then alexandrite definitely has better values. The hardness of alexandrite is 8.5 on Mohs’ scale while emerald is only 7.5. The specific gravity is between 3.69 and 3.75 values are way ahead of emerald which is just 2.70. Even the refractive indices are higher1.74 and 1.75 for alexandrite whereas those for emerald are only 1.57 and 1.58.

In fact the alexandrite properties are more towards those of ruby which has hardness of 9, specific gravity 3.99 and refractive indices 1.76 and 1.77. Interestingly all these gems, alexandrite, emerald as well as ruby owe their colours to the element chromium, the colour change from green to red in alexandrite, the deep green in emerald and the blood red in ruby.

The microscopic inclusions have been investigated and well documented for Russian Alexandrite. Karl Schmetzer has elaborated on growth structures which are frequently associated with colour zoning. Mineral inclusions include phlogopite mica flakes, fluorite and apatite crystals. Often there are numerous internal fractures filled with liquid and gas sometimes with crystals of mica. Gases phase have been identified as CO₂.

There are two stages of alexandrite crystallization within the main emerald bearing ore bodies called glimmerites. In the first stage chrysoberyl and emerald were formed within the mica schists or plagioclase-rich host rock. In the second stage emerald, plagioclase and alexandrite crystallized making it a sequential process of mineral formation.

Cat’s effect seen in gems is called Chatoyancy. Alexandrite has numerous channel or needle like inclusions that can give rise to cat’s eye effect if the gem is cut in cabochons. Russian Alexandrite does exhibit beautiful chatoyancy or cat’eye effect. In this regard there are also Sri Lankan Alexandrites that display cat’s eye as well as asterism (star effect).

Colourimetric techniques have been used to elaborate on how the colour change in alexandrite takes place. It is important to know that there may be green chrysoberyl which may not always show the colour change effect. In fact the green colour chrysoberyl from Andhra Pradesh may not show this colour change in which case it would not qualify to be Alexandrite.

Alexandrite is very well described in a recently published technical book by famous German mineralogist Karl Schmetzer. It is very interesting to note that Russian alexandrite was first discovered in the historically famous emerald mines of the Ural and was considered as the by-product of emerald production. Schmetzer gives a very vivid description of how the first emerald was found in 1830 by a farmer of the Beloyarsk district, in the roots of a fallen tree at the banks of Tokovaya River. This further led to exploration of number of mines having emerald deposits of astronomical value. These mines as well as the Malysheva mine are a part of the Uralian gemstone Belt where Alexandrites are recovered.

by Jayshree Panjikar

Trade Journal "All that Glitters", December 2010, page 49
published by Express Publications (Madurai) Limited, Queens Road,
Bangalore - 560 001, India

In September, we featured a notice regarding the impending publication of Russian Alexandrites by Karl Schmetzer (with contributions from George Bosshart, Marina Epelboym, Lore Kiefert and Anna-Kathrin Malsy). For this edition of our newsletter we thought a scholar's perspective on the volume might be interesting, so we approached Lisbet Thoresen, whose own work on gemstones, especially their historical background—discovery, naming and use—are prominent topics in this book.

The book is available from the publisher. It also is available at Tucson from Antoinette Matlins. See her here:

* AGA Conference, February 2, 8:30 a.m. – 5:30 p.m., Tucson * Marriott University Park Hotel AGA Gala, February 2, 6:30–11:00 * p.m., Tucson Marriott University Park Hotel Quantum Leap, booth * #30, in the Galleria at the AGTA GemFair, Tucson Convention * Center

The history of alexandrite has been shrouded in mystery and obfuscation since its discovery in the Urals, Russia, in 1833. Despite its commercial value and desirability as a rare collector gemstone, mineralogical studies on this color-change variety of chrysoberyl, especially the Russian material, have been limited until recently. In 2010, Dr. Karl Schmetzer produced a comprehensive and authoritative book on this subject entitled Russian Alexandrites. For the first time, this book reconstructs an accurate history of the gemstone through original letters and reports translated from Russian, French, Swedish and German, as well as historical photographs obtained from obscure archives. This book also provides an insight into the study of minerals of the 1830s to 1850s, when mineralogy was just beginning to become a science.

Marina Epelboym and Karl Schmetzer frame the story first by describing the geological setting in which chrysoberyl and alexandrite (and also phenakite) were discovered—as associated minerals in the emerald bearing zones of the Izumrudnye Kopi belt, or Tokovaya area, northwest of Ekaterinburg, which, after Colombian sources, are the most commercially significant historical emerald deposits in the world. Always regarded as a secondary mineral to emerald, Schmetzer estimates the ratio of emerald to alexandrite ranges between 100:1 and 200:1. Because the primary mining interests focused on emeralds, the history and development of the Russian mines where alexandrites were first discovered inextricably interweaves the story of alexandrite with that of some of the most important emerald specimens ever found. This aspect of alexandrite’s history is taken up in the book’s next chapter by Schmetzer.

The principal author provides a fluid narrative relating the history of the famous emeralds recovered from the Tokovaya area and their passage through the hands of illustrious collectors and museums, including the Kokovin emerald, a 400 gram emerald that was lost or stolen in 1835; the Leuchtenberg emerald druse, a group of 20 crystals en matrix found in 1831 and weighing 6265 grams (first published by von Pott in 1842); the Kochubei emerald, found in 1831 at the Sretensky Mine and weighing an astounding 2226 grams. Among the alexandrite finds, the most important ones were all discovered prior to 1840, and pre-eminent among them is a crystal group known as Kochubei’s druse (pictured below). Also in this same chapter, Schmetzer chronicles the discovery, naming and uses of Russian alexandrite in the 19th century. Named in 1842 in honor of the Tsarevich, the future Tsar Alexander II of Russia (r.1855–81), the author also presents the correspondence, publications, photographs and drawings that establish an accurate timeline and context concerning alexandrite’s early history.

In 2005, the Tsar Emerald Corporation, a Canadian company, secured licensing agreements to operate the Malysheva Mine, one of the seven principal mining sites which were discovered prior to 1840. In 2007, Dr. Schmetzer and Dr. Lore Kiefert were able to visit the mine and perform the first mineralogical studies on specimens that had been unearthed after 2000 from the Malysheva Mine. As volume editor and principal author of Russian Alexandrites, Schmetzer has drawn together data gathered on alexandrites and yellowish green to yellow green chrysoberyls in various collections, both private and public, in Russia, Germany, Austria and Great Britain—covering material from a time period spanning more than 175 years. Gemological, mineralogical, morphological and colorimetric data are presented in separate chapters, each detailed and copiously illustrated with color plates, photomicrographs, spectra, schematic diagrams, plots and charts.

Chapter 6 presents gemological and mineralogical studies performed by Schmetzer and Kiefert, which employed analytical tools, including electron microprobe, SEM-EDX, energy-dispersive X-ray fluorescence (EDXRF) and micro-Raman spectroscopy in order to obtain quantitative data and corroborative identification of inclusions. Numerous photomicrographs complement the discussion of alexandrite’s inclusions, distinctive growth structure and twinning.

Beginning with a discussion of the early work of mineralogists on the recent finds from the Central Urals, in Chapter 5, Schmetzer presents an in-depth examination of the morphology and twinning in chrysoberyl and especially alexandrite, elaborating in detail the distinctive habit of single crystals, single contact twins and cyclic twins or trillings. Numerous drawings by the author and photographs of historical specimens illustrate the discussion on the morphological variations of crystals originating from the Tokovaya area.

Chapter 7 is devoted to an investigation into the nature of chatoyancy in alexandrites and chrysoberyls from different gem-producing regions of the world, as well as the rare phenomenon of asterism in chrysoberyl from Sri Lanka—a subject that has received scant attention previously. Chapter 8 compares the growth patterns of natural alexandrite and its synthetic counterpart. The last chapter, authored by Anna-Kathrin Malsy, discusses origin determination and the use of several analytical tools, primarily laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to obtain trace element chemistry in specimens from Russia; Hematita, Brazil; India; Sri Lanka; and Lake Manyara, Tanzania. Operating conditions and data acquired are described and characteristic features useful for making separations are discussed. This chapter, featuring ternary diagrams and plots, is a useful benchmark for future studies on chrysoberyls and alexandrites from other localities.

This volume aims to be a handy reference as much as it aims and succeeds at being a meticulously detailed and comprehensive work on Russian alexandrite: the Appendices and Timetable feature tables on primary mining localities, physical data on alexandrite and green chrysoberyls, English-German transcription of significant names and milestone events. The achievement of this book is not only its exhaustive treatment of the subject, unprecedented for the scope and detail presented, but also its historicity. It is a fascinating chronicle of alexandrite’s Russian origin and labyrinthine odyssey through time—a painstakingly researched story replete with intrigue, tragedy and epochal sweep worthy of translation to motion pictures. Such a rare and special gemstone deserves no less than the able and thorough treatment it receives in this book.

Lisbet Thoresen

Pala Mineralis - Minformation 24/7

>http://www.palaminerals.com/news_2011_v1.php#russian_alexandrites

Das Buch in englischer Sprache behandelt detailliert und systematisch Alexandrite aus Russland, die seit den 1830er Jahren in den Smaragdgruben an der Tokowaja im Ural gefunden werden und als „Nationalstein“ Russlands gelten.

Nach der Einleitung folgt in Kapitel 2 ein kurzer geschichtlicher Überblick über die Smaragd-Minen im Bereich der Tokowaja. Kapitel 3 beschäftigt sich mit der Geschichte der Entdeckung und historischen Beschreibungen der russischen Alexandrite, der Namensgebung und der historischen Verwendung.

Kapitel 4 gibt einen Überblick über russische Alexandrite in mineralogischen Museen in Russland und weltweit sowie in privaten Sammlungen.

In Kapitel 5 wird auf die Kristallformen und Zwillingsbildungen eingegangen. Die mineralogischen und gemmologischen Eigenschaften sind Inhalt von Kapitel 6. Den größten Teil dieses Kapitels umfassen die mikroskopischen Eigenschaften der russischen Alexandrite, unterteilt in strukturelle Merkmale wie Wachstums- und Zwillingsstrukturen sowie Mineral- und Flüssigkeitseinschlüsse.

Kapitel 7 beschäftigt sich mit Alexandritkatzenaugen aus Russland verglichen mit dem Katzenaugeneffekt bei Alexandriten aus Sri Lanka sowie Sternchrysoberyllen ebenfalls aus Sri Lanka.

Ein Vergleich der Wachstumsmerkmale von russischen Alexandriten mit Steinen anderer Vorkommen sowie synthetischen Alexandriten ist Inhalt von Kapitel 8.

In Kapitel 9 wird auf kolorimetrische Daten eingegangen sowie auf die Unterscheidung zwischen Alexandrit und von gelb nach grün farbwechselnde Chrysoberylle.

Kapitel 10 beschäftigt sich mit der chemischen Zusammensetzung im Spurenelementbereich und sich daraus ergebenden Möglichkeiten der Herkunftsbestimmung von Alexandriten.

Es folgen ein Anhang mit verschiedenen Tabellen zu den einzelnen Kapiteln, ein ausführliches Literaturverzeichnis und das Inhaltsverzeichnis.

Das Buch über russische Alexandrite bietet wertvolle Informationen für Mineralogen und Gemmologen, Edelsteinhändler und Sammler.

Dr. Ulrich Henn

Gemmologie (Z. Dt. Gemmol. Ges.) 59/3-4, 2010, Seite 117

Das vorliegende Buch über die „Russian Alexandrites“ gehört natürlich zu den TOP-Werken, stellt ohne Zweifel ein internationales Fachbuch dar und ist daher in englischer Sprache abgefasst.

Der Mythos des äußerst seltenen Edelsteins wird in diesem Buch allumfassend abgehandelt; so werden neben der Geschichte und der Entdeckung auch die mineralischen Charakteristika in unzähligen Abbildungen und Hochglanzfotos für den Leser spektakulär beschrieben bzw. aufgezeigt. Dieses Buch ist in seinem Inhalt ein unschlagbares Fachbuch, trotzdem versteht es der Autor, den Leser auf eine Reise in ein spannendes Abenteuer rund um die Russischen Alexandrite mitzunehmen.

Das Fachbuch ist äußerst strukturiert aufgebaut (das Indexverzeichnis ist perfekt) und in einer handlichen Form gehalten. Folgende Kapitel werden abgehandelt: 1: Introduction, 2: The emerald mines in the Tokovaya area – a short historical overview, 3: Discovery, naming and historical use of the Russian alexandrite, 4: Russian alexandrites in mineralogical museum and in the trade, 5: Morphology and twinning, 6: Mineralogical and gemological properties, 7: Alexandrite cat`s-eyes and chrysoberyl stars, 8: Comparison of growth patterns of Russian, other natural and synthetic alexandrites, 9: Colorimetric data of Russian alexandrite and yellowish green to green chrysoberyl, 10: Trace element chemistry and locality determination. Eine Danksagung am Anfang und ein Nachspann mit vielen zusätzlichen Informationen wie u.a. optische Daten und Referenzen runden dieses Buch ab.

Dieses Buch ist ein „must-have“ für alle Mineralien- bzw. Edelsteininteressierte.

Der Preis von 34,80 Euro ist absolut gerechtfertigt.

Jürgen GÖSKE, 91233 Neunkirchen am Sand

der Aufschluss Jg. 62 März/April 2011

Although the main author is Karl Schmetzer Russian Alexandrites has many contributions from leading European figures including George Bosshart, Marnia Epelboym, Dr Lore Kiefert and Anna-Kathrin Malsy. The aim of this very well illustrated book is to look in detail at Russian alexandrites and this is exactly what it does.

Simply put this is no coffee table book for the general public but neither will it necessarily appeal to a large portion of the gem and jewellery industry, despite its in-depth look at the history of Russian alexandrites since the 1830s. It has a slightly slow start, with the first two chapters dealing more with emerald than alexandrite, but this diversion is an important reminder of the close synergy these materials have in this region.

Russian Alexandrites is a treasure trove for mineralogists and serious gemmologists especially when it comes to the morphology of alexandrite crystals from Russia. In many ways this book is more akin to an expanded research paper detailing the scientific findings based on research carried out on a selection of stones mined in Russia over the last 180 years. Not surprisingly, considering the interests of the author, there is a whole chapter dedicated to the colourimetric data of Russian alexandrites and it is obviously a subject he feels very passionate about.

Both synthetic alexandrite and alexandrites from other localities are touched upon, although gemmologists looking for a comparison to help with differentiating between these materials will not find a quick step-by-step “how-to” guide here. Rather the author stresses the difficulty of determining the origin of a stone without the required experience.

Russian Alexandrites fulfils its brief in relation to the analysis of Russian alexandrites and as such will be an invaluable reference. However, as its title warns, those looking for a broad overview of chrysoberyl and alexandrite will find this book too specialised for their needs. (Russian Alexandrites by Karl Schmetzer is also mentioned in Prof Dr H.A. Hänni’s article on Chrysoberyl in this journal pp 38-43. – ed.)

Lorne Stather, Dir. of Education, Gem-A, London

The Journal of the Gemmological Association of Hong Kong, 2010 Volume XXXI

Es gibt einige seltene Mineralien, deren Farbe sich je nach Beleuchtung erheblich verändert: Dies macht sie als Edelsteine besonders kostspielig. Am bekanntesten ist in dieser Hinsicht der Alexandrit, eine Varitetät des Chrysoberylls, das heisst Aluminiumberyllat Al₂BeO₄. Auch in der belebten Natur gibt es nur wenige Verwandlungskünstler: Das Chamäleon und einige Fischarten bringen es fertig, Farbe und Musterung ihrer Haut der Umgebung anzupassen. Diese optische Tarnung bringt einen hohen Überlebensvorteil, darum wurde sie von der Evolution selektioniert und zu hoher Perfektion gebracht. Ganz anders ist es mit dem changierenden Alexandrit. Beim blau- und violettreichen Tageslicht ist dieser mit Mohs 8,5 sehr harte Edelstein blaugrün, im rotstichigen Kunstlicht und besonders im Kerzenlicht erscheint er purpurn bis rot. Diese Erscheinung wird als Alexandrit-Effekt bezeichnet und ist auf zwei lichtoptische Absorptionsmaxima im roten beziehungsweise blauen Spektralbereich zurückzuführen. Abgesehen von Exoten zeigen nur noch die sehr seltenen, alexandritartigen Granate aus Sri Lanka und Ostafrika einen ähnlichen Effekt. Chrysoberyll ist normalerweise goldgelb, nur die Alexandrit genannte Spielart hat die Eigenart des Changierens, die auf den Eisen- und Chromgehalt des Edelsteins zurückzuführen ist. Dass die wissenschaftliche Untersuchung des Alexandrits vorwiegend in schwer zugänglichen russischen Publikationen „versteckt“ wurde, liegt wohl daran, dass der Edelstein eben ur-russisch ist - obwohl man ihn auch in Sri Lanka, Myanmar, Madagaskar und Brasilien findet. Er wurde im Ural bei Swerdlowsk (heute Jekaterinburg) entdeckt und seit zirka 1830 abgebaut.

Seinen Namen erhielt er vom Zarewitsch Alexander, dem nachmaligen Zaren Alexander II. Allerdings war der Alexandrit nur ein Nebenprodukt anderer, wirtschaftlich bedeutender berylliumhaltiger Mineralien, insbesondere Smaragd. im Zweiten Weltkrieg wurden sie im Zusammenhang mit der damals entwickelten Nukleartechnik von strategischer Bedeutung, was absolute Geheimhaltung mit sich zog. Denn das Leichtmetall Beryllium (die Dichte beträgt lediglich 1,85 g/cm3) ist für Neutronen nahezu durchsichtig. Dasselbe gilt übrigens für Röntgenstrahlen, darum haben Röntgenröhren ein Berylliumfenster zur Auskoppelung der Strahlung.

Es ist höchst erfreulich, dass dem in jeder Hinsicht faszinierenden Alexandrit nun eine so akribisch recherchierte und berauschend schön illustrierte Monographie gewidmet ist. Der ausführliche historische Teil lässt nichts zu wünschen übrig, bezieht sich auf bisher im Westen kaum bekannte Originalquellen und lässt die interessanten, politischenlie und wirtschaftlich mächtigen Männer wieder aufleben, die sich schon früh für den Alexandrit interessierten. Ihre Sammlungen spektakulärer Kristalle, einzeln oder noch in ihre Glimmerschiefer- beziehungsweise Granitpegmatitmatrix eingebettet, gerieten letztendlich in Museen, vorwiegend in Russland, wo sie bewundert und wissenschaftlich untersucht werden können. Auch in Bezug auf die Kristallographie‚ die Mineralogie, die Gemmologie, die Spektroskopie und den Spurenelementgehalt des Alexandrits bietet das Buch eine Fülle anschaulich illustrierter lnformation. Kurz eingegangen wird auf den synthetischen Alexandrit, die sehr seltenen Steine mit Katzenaugeneffekt sowie die Vorkommen ausserhalb Russlands. „Flussian Alexandrites“ sollte in keiner Handbibliothek des als Profi oder Amateur für Edelsteine Engagierten fehlen.

Having been able to facilitate the study of alexandrite specimens in the Natural History Museum collections with renowned gemmologist and author Karl Schmetzer, it was with eager anticipation that I received his new book Russian Alexandrites. With contriburtions from George Bosshafi, Marina Epelboym, Dr Lore Kiefert and Anna-Kathrin Malsy, the book seeks to be an all encompassing work on this valuable variety of chrysoberyl; the authors' intentions being made clear in the short introduction whereby they state that although much been written on alexandrite,there is a paucity of data concerning inclusions, microscopic features and indicators of provenance.

My first impression of the book is of quality, with a simple but elegant group in both daylight and incandescent light. The book is slightly larger format at 275x275 mm, is superbly produced, and beautifully illustrated with over 200 coloured figures, photographs, maps and diagrams.

The introduction gives a summary of the geological setting of the Uralian deposits and recent mining activity including photographs of Schmetzer and Kiefert's visit to the Malysheva mine in 2007. Chapter 2 follows with a historical overview of the Tokovaya area, and whilst the author notes that this has been the subject matter of numerous publications beforehand, this is an excellent summary. Chapter 3 describes in great detail the discovery, naming and historical use of Russian alexandrite. This chapter can be regarded as the definitive chronology of Russian alexandrite, the author having excelled in bringing together a wealth of information that includes historical literature, family archives, published reports, illustrated portraits and discussions of the more famous specimens which includes emerald as these two gem varieties are so closely associated in the deposits in the Urals. Chapter 4 gives a brief overview of Russian alexandrites in mineralogical Museums and in the trade, the author having comprehensively studied over 400 alexandrite crystals, crystal groups and gemstones from major European and Russian museums and private collections. This leads us into chapters 5 and 6 which are closely linked. Chapter 5 on morphology and twinning is extensively illustrated with photographs of alexandrite crystals. The chapter is so ,photo rich' that it gives the impression of being able to personally browse the holdings of those great collections. I particularly liked how these images are compared to equivalent crystal drawings by the author who has colour-coded the faces to make it easy to distinguish the different forms and development of complex twinning. Chapter 6 looks at mineralogical and gemmological properties with beautifully illustrated sections on typical microscopic features such as twinning and inclusions. Chapter 7 discusses the chatoyant effects of alexandrite and chrysoberyl, and although Russian cat's-eyes are discussed, the chapter also includes sections on Sri Lankan material. Chapter B is very short at only three pages, but discusses the comparison of growth patterns of Russian, other natural and synthetic alexandrites. Chapter 9 discusses the colorimetric data of Russian alexandrite and yellowish gfeen to green chrysoberyl using the CIELAB colour space model, with interesting discussion as to the practical application of colorimetry in provenance and nomenclature studies. Chapter 10 looks at trace element and locality determination of Russian alexandrites using LA-ICP-MS. As a relatively recent and increasingly important technique used in gemmology, I was pleased to see a short but concise summary of the principles of the application itself. Aside from the appendix of seven tables of data, transcription of names, historical timetable, and index, the exhaustive research that the author has undertaken is reflected in an extremely useful and comprehensive reference list. Overall, Russian Alexanrrites is an excellent scholarly work and is the choice for anyone looking for a wealth of information on this most enigmatic of gem varieties. Indeed, it is one of the best 'single species' volumes ever published. There is more to this book than the title suggests, especially in the later chapters where comparisons and references to chrysoberyl and alexandrites fiom other localities including synthetics are made. The book is well laid out and is notable for its beautiful and relevant illustrations. This is a book for historians, enthusiasts, mineralogists, gemmologists and researchers and with its low price is an essential buy for any reference collection.

Alan Hart

The Journal of Gemmology 2=10, vol. 32, No. 1-4, page 113

Karl Schmetzer et ses collaborateurs, notamment du laboratoire Gübelin, nous proposent une monographie en anglais sur les alexandrites russes. Jusqu'à présent, la documentation disponible sur le sujet n'était certes pas à la hauteur de la renommée des gemmes concernées. Peu d'ouvrages et seulement quelques articles sont consacrés au chrysobéryl, même si l'on parle plus souvent de sa variété à changement de couleur, l'alexandrite. N'oublions pas que l'alexandrite, qui ne fait pas partie des "quatre précieuses", atteint cependant des prix comparables à celles-ci, ainsi qu'un certain nombre d'autres gemmes oubliées par cette classification un peu brutale (on peut penser au jade, opale, perles fines, saphir padparadscha etc.). C'est donc une étude bienvenue et dès le premier abord facile à lire, grâce à l'abondance d'illustrations couleur et la qualité de la mise en page.

Comme l'histoire de l'alexandrite est indissociable de celle des mines d'émeraude, où ces deux gemmes continuent d'être trouvées aujourd'hui, le tout premier chapitre est naturellement consacré à une brève présentation de la zone de Tokowaja.

L'attention se resserree ensuite sur une étude détaillée de la découverte de cette gemme, la façon dont elle fut dédiée au tsarévitch Alexandre, et d'une façon plus générale l'histoire de cette gemme jusqu'à nos jours. Nombre de documents d'archives sont présentés, dans un narratif assez fluide. Cette partie plaira autant à l'historien de la bijouterie qu'à l'amateur d'histoires glamour à conter au client.

Un bref chapitre s'intéresse aux alexandrites russes trouvées dans les musées et dans la profession. L'essentiel des échantillons étudiés viennent de musées, où les auteurs se sont beaucoup intéressés aux échantillons bruts, plus abondants que les pierres taillées de qualité.

Suivent plus de 20 pages consacrées à la morphologie des cristaux et des nombreuses macles, exercice auquel Karl Schmetzer excelle et s'est souvent livré. Les photos sont accompagnées de dessins idéalisés multicolores avec un code couleur cristallographique. Ceci aide bien à expliquer d'abord la cristallographie des rares monocristaux, mais surtout 1a zoologie des macles : simple ou multiple, cyclique, par contact ou pénétration, avec ou sans angle rentrant, en colonne ou bipyramide, etc.

Les propriétés minéralogiques et gemmologiques sont abordées dans le chapitre 6, qui contient presque exclusivement une étude détaillée de la morphologie d'après les figures de croissance et inclusions des gemmes vues en immersion, deux grandes spécialités de l'auteur. Le document réussit le tour de force d'évoquer les "propriétés chimiques" sans donner la moindre analyse quantitative et expédie indice de réfraction et densité en moins de quatre lignes d'une demi colonne, ce qui est clairement décevant pour le gemmologue pratiquant.

Quelques pages sont consacrées aux alexandrites "œil de chat" de Russie et du Sri Lanka et aux très rares alexandrites étoilées à quatre branches. Un court chapitre résume les données sur la morphologie de l'alexandrite naturelle et synthétique, suggérant que l'absence de la dipyramide peut indiquer qu'une alexandrite est d'origine ouralienne.

L'effet alexandrite, c'est-à-dire le changement de couleur perçu entre différents éclairages, est abordé de façon colorimétrique dans l'espace CIELab, et comparé avec des pierres jaunes et vertes à priori sans changement de couleur. L'importance de l'orientation cristallographique pour observer un changement de couleur plaisant est soulignée. Les auteurs choisissent de mesurer le changement de couleur, par la distance entre couleurs ΔE sans justifier leur choix (alors que cette mesure n'implique pas forcément de déplacement sur la roue des couleurs, on peut rester dans le vert avec un ΔE élevé), plutôt que le changement d'angle de couleur Δh (qui mesure l'ampleur du déplacement sur la roue des couleurs, c'est-à-dire, précisément, l'ampleur du changement de couleur, même si la saturation, c'est-à-dire la vivacité de la couleur, peut varier).

Le dernier chapitre, rédigé par Anne- Kathrin Malsy, utilise la chimie des éléments en trace pour distinguer les alexandrites ouraliennes de celles d'autres gisements. La méthode de mesure est la spectrométrie de masse avec ablation laser (LAICPMS). Il est préconisé que les alexandrites russess se distinguent par les concentrations les plus fortes en germanium (Ge) et tantale (Ta), des traces "élevées" en étain (Sn) et des valeurs intermédiaires pour le bore (B) et le gallium (Ga). Néanmoins il est nécessaire d'utiliser un diagramme ternaire en concentration Cr - Ga multiplié par 5 - Ge multiplié par 1000 pour séparer le domaine des alexandrites du Sri Lanka de celui des alexandriles russes, qui restent donc assez proches.

Quinze pages d'annexe contiennent des indications chiffrées gemmologiques, chimiques, historiques et lexicales ainsi qu'une liste de bibliographie parliculièrement riche en références allemandes.

Un scientifique pourrait s'étonner de certains détails: il n'y a pas de définition dès le début du terme alexandrite, on aurait aimé des mesures plus détaillées pierre par pierre, avec le lien entre les différentes propriétés gemmologiques expliquées (par exemple entre indice de réfraction, densité, chimie et couleur). L'esthète regrettera l'absence de photographie de haute qualité de pièces spectaculaires pourtant disponibles via les maisons de vente aux enchères ou les collectionneurs privés (on note toutefois de belles compositions graphiques de brut par Thomas Hainschwang, dont une fait la couverture du livre). Malgré des nuances, nous avons enfin une monographie de l'alexandrite qui comblera les amateurs d'Histoire et d'histoires, de cristallographie pointue, les collectionneurs d'alexandrite, de chrysobéryl et de macles. Cet ouvrage est également à recommander à tout gemmologue sérieux soucieux de mieux connaitre cette gemme rare et chère.

Dr Emmanuel Fritsch Professeur à l'Université de Nantes

Revue de Gemmologie A.F.G, Mars 2011 N° 175

Alexandrite, the famous color-change variety of chrysoberyl, has numerous articles devoted to its study, but never has a book with such detail been compiled to focus on this extraordinary gem. If you know absolutely nothing or you thought you knew everything about alexandrites, then you must read Russian Alexandrites. The book expertly covers the rich history, mineralogy, gemology and chemistry of Russia's national gemstone.

Dr. Karl Schmetzer, along with contributions from George Bosshart, Marina Epelboym, Dr. Lore Kiefert and Anna-Kathrin Malsy, has masterfully composed the most comprehensive study of this phenomenal gem. Schmetzer is an independent gemological researcher specializing in the mineralogy, characterization, origin, cause of color and treatment in natural and syntheticg em materials. A prolific author, he has published nearly 400 papers and articles. He is also an editorial board member of Australian, British and French gemological journals.

The 141-page book, divided into 10 chapters, contains numerous color illustrations, charts, graphs and maps to help the reader navigate through the treasure trove of information. In the first three chapters, Schmetzer covers details of Russian alexandrite's fascinating history from its initial discovery, to the first characterization, to its naming and recognition by various authorities in mineralogy. He begins with a brief summary of a 2007 visit to the famous Malysheva mine where alexandrite was first discovered in 1833. At that time, this mine was known as the Mariinnsky Mine but was renamed the Malysheva mine in 1927. The second chapter provides a brief historical overview of the entire Tokovaya mining area in the Ural Mountains where alexandrite is still being found today. Before alexandrite was discovered, this area was already known for its emerald production, which began in 1830. This chanter also provides details of ownership and production in the emerald and alexandrite mines which closely followed the transition from Imperial rule to the revolution of 1917, then on to their nationalization for beryllium mining during both World Wars, nuclear production needs after 1945, and finally back to gemstone mining from the 1970s to the present. Based on original documents and publications from the 1830s and 1840s, Schmetzer goes on to explain the fascinating historical, geological, and mineralogical connection between emerald, chrysoberyal and alexandrite in the Uralian deposits. In 1842, Alexandrite was named in honor of the Tsarevich Alexander Nikolaevich who later reigned as Tsar Alexander II from 1855 to 1881. This name was even more appropriate because red and green represented the military colors of Imperial Russia.

The fourth chapter covers Russian alexandrites inn mineralogical museums and in the trade. Approximately 400 alexandrite crystals and crystal groups from museums and private collections were examined for the research conducted by the author and his contributors. The museums that provided information and materials for study included four in Russia, one in Austria, one in England and two in Germany. Chapter five provides precise details of morphology and growth characteristics using photos and colorful drawings that are quite easy to understand. In chapter six, which focuses on mineralogical and gemological properties, Kiefert contributes her Raman and X-ray fluorescence analysis expertise. Raman spectra of some associated assemblage minerals as well as Russian alexandrite trace element characteristics, acquired through X-ray fluorescence analyses, are featured. Schmetzer, famous for his expertise in structural characteristics, provides numerous immersion microscope photos showing detailed growth characteristics and typical inclusions. These two chapters could be considered textbook examples of how to properly describe and characterize the morphology and inclusion characteristics of any mineral or gem.

Chapter seven explains how needle-like inclusions in alexandrite contribute to chatoyancy (cat's eyes) and asterism (stars). Chapter eight compares growth patterns of Russian alexandrites with other natural as well as synthetic alexandrites. Chapter nine, with contributions from George Bosshart's expertise in spectroscopy and color theory, focuses on colorimetric data and how the CIELAB color space model can be used to more accurately measure and describe color change in alexandrite. Detailed polarized and non-polarized spectra of a synthetic alexandrite cut into a cube for more accurate measurements of the three crystallographic axes are also presented. In the final chapter, Anna-Kathryn Malsy provides a summary on origin determination in gemology and how traditional, combined with advanced testing techniques, may be applied to the geographic origin determination of Russian alexandrites. She provides an excellent description of the principles of Laser Ablation Inductively Coupled Mass Spectrometry (LA-lCP-N/S) along with a schematic diagram. Also featured are numerous ternary trace element diagrams that, when combined with other typical criteria, may be used for the separation of Russian alexandrites from other sources. The book concludes with an appendix containing seven tables and a transcription of names, a timetable from 1829 to 1913, and seven pages of useful references.

Schmetzer's attention to historical details, coupled with his contributions to the understanding of the external and internal structural properties of chrysoberyl and alexandrite, will prove invaluable in furthering the identification and differentiation of all alexandrites. His contributing authors provide valuable information and apply techniques that will also aid in the future characterization and identification of this beautiful and historically important gem. This work is one of the most comprehensive books on a single gem variety that this reviewer has had the Pleasure of reading.

Edward Boehm

InColor, Spring 2012, issue 19

Alexandrite, a gem variety of the mineral chrysoberyl, is much sought after because of the distinct color change it exhibits between daylight and incandescent light. The rarity of gem-quality alexandrite leads many observers to consider it as important as diamond, ruby, sapphire, and emerald. It is also regarded as the national gemstone of Russia. In this fascinating and comprehensive book, Dr. Karl Schmetzer and contributors present an overview of alexandrite mining in Russia’s Ural Mountains, the naming and historical use of the gem, its characteristics, and its importance in the gem trade.

The author points out that alexandrite has been mined since about 1833 and was named for young Alexander Nikolaevich (later Czar Alexander III, 1855–1881). Here he reproduces the first scientific publication on the gem and traces the history of two extraordinary samples, the Leuch tenberg emerald druse and Kochubei’s druse.

Chapter 5 reviews morphology and twinning. Dr. Schmetzer notes that most alexandrites occur as repeatedly twinned crystals with pseudo - hexagonal dipyramidal habits. As is typical of the book, this chapter features beautiful diagrams and photos of real-world examples.

The chapter on mineralogical and gemological properties includes lengthy sections on structural properties (twinning and growth structures) and mineral and fluid inclusions in faceted stones. The majority of the mineral inclusions have been identified by Raman spectroscopy as phlogopite, while fluorite and apatite crystals were identified in a few samples. The chapter concludes with a section on mineral assemblages, growth conditions, and growth sequences. As the author notes, various studies have shown that the main occurrences of alexandrite are within emerald-bearing ore bodies, also known as glimmerites, in which it is possible to deduce two stages of alexandrite crystallization. In the first stage, emerald and alexandrite formed within mica schist or a phlogopite- rich host rock. In the second stage, additional emerald and alexandrite crystallized, along with plagioclase.

Subsequent chapters present chatoyant alexandrite, growth patterns, colorimetric data, and trace-element chemical composition (as determined by LA-ICP-MS), and locality determination. Chemical analyses show that alexandrite from Russia’s Tokovaya mines can be distinguished on the basis of its chromophores (V, Cr, Fe) and its B, Ga, Ge, Sn, and Ta contents.

The appendix contains eight tables of information on such topics as morphological properties of Russian alexandrites, characteristic angles observed in Sri Lankan material from faces of the [001] zone, properties of Czochralski-grown synthetic alexandrite, colorimetric parameters of alexandrite and chrysoberyl from the Urals, and trace-element and ultra–trace element contents of alexan drite and “green chrysoberyls” obtained by LA-ICP-MS.

In general, the book is comprehensive and the writing and illustrations are clear and understandable. My complaints are few. The quality of some photos is less than ideal, and the tables would probably be better placed in the body text rather than in an appendix. Overall, though, this is a superb publication that belongs on the desk of anyone interested in alexandrite, emerald, chrysoberyl, and the history of Russian gem mining.

LEE A. GROAT, University of British Columbia, Vancouver

Gems & Gemology (Summer 2012)