corundum, chemistry.2, gems

Schuh: Very scarce. The Cristallographie ranks as one of the great contributions to the science of crystals. In it Romé de l'Isle attempted to make a comprehensive classification of crystals. By the time he wrote this volume, he was extremely familiar with the subject, and this work greatly supassed all previous works in scope and detail. To apply his classification, he adopted a morphological approach in which he attempted to relate the diverse forms of crystals of the same substance. As a general morphological concept he introduced the idea of the “primitive form.” All crystals of the same inorganic substance, no matter how different in appearance had a fundemental and common geometrical form-the primative form-to which their actual crystal shapes related. The justification for this idea was derived from the previous work of Carl Linneaus who had tried to expain the genesis of minerals by means of an analogy with the procreation of living creatures, and classified cystals by the similarities of their crystallized forms. In this first edition of the Cristallographie, Romé de l'Isle identifies 110 crystal forms by which minerals crystallize. Grouped under each of these shapes are described the minerals that exhibit similar habit, including the approximate angles between crystal faces. These forms were all derived form a common saline ingrediaent in every mineral that worked at a molecular level. Although he believes that these primitive forms existed, it is never made clear how they should be defined for any group of crystals. Romé was able to greatly expand upon this idea in the second edition [which see below]. An annotated bibliography compiled by Romé is listed on pages xvii-xxviii.

gems, glyptic, engraved gems, agate, cameo, intaglio

Sinkankas: This is the earliest analytical work on engraved gems and one that fully retains value even today. However, the two volumes are actually distinct works combined by the author and publisher—P.J. Mariette—for convenience. The first volume is by far the more important, offering an authoritative summary of knowledge on engraved gems, significantly enhanced by lengthy discourses on previous works and a nearly exhaustive bibliography of published sources. It begins with a general history of engraved gems, followed by an essay on modern gem engraving and engravers, and a large section describing the gems, divided into four chapters: I. Descriptions of gemstones and other materials used in engraving (pp. 153–194), including diamond, ruby, garnet, emerald, beryl, peridot, chrysolite, topaz, amethyst, quartz varieties, opal, lapis, coral, amber, ivory, and glass, drawing mainly on Pliny, De Berquen, and De Boodt; II. Lapidary processes, tools, and equipment required for gem engraving, with engraved plates showing an atelier, an engraver at work, and diagrams of engraving tools and accessories; III. Falsifications; IV. Making impressions. The final portion (pp. 239 to end) contains commentary on previous engravings used for illustration and the extensive bibliography noted earlier. In contrast, the second volume is entirely devoted to descriptions of the gem cabinet of Louis XV (1710–1774), King of France—this section drew strong interest from C.W. King (Antique Gems and Rings, vol. 1, pp. 465–466), who praised its content but criticized the engravings, drawn by Bouchardon (1698–1762), as being in too loose and flowing a style to convey an accurate idea of the originals. The cabinet featured gems of sapphire, zircon, malachite, jade, turquoise, and others in faceted forms, with the project supervised by the noted antiquarian Comte de Caylus (1692–1765). Vinet (1620) offered a long summary of the work, praising it as a classic still of use today, though he and others, including King, criticized the quality and accuracy of the engravings. The work was also attacked by Giulianelli (Memorie degli intagliatori, 1773) and Natter (Traité de la méthode… graver en pierres fines, 1754). Reinach (Pierres gravées, pp. 85–110) reproduces a number of its plates. Furtwängler (Die antiken Gemmen, vol. 3, p. 413) called the first volume broad in scope and written in an easy style with intelligent judgment, but joined critics of the second volume, calling its text “without learning and without citations,” and noting that antique and Renaissance gems were indiscriminately mixed—Mariette, he said, was as uncritical as Gravelle. See also Zazoff (Gemmensammler, 1983, pp. 127–133) for modern views.

corundum, history.1, gems

Sinkankas: In a quite remarkable essay which forms the Preface, Woodward extols the mineral wealth of Britain, pointing out its production of the useful metals as tin, lead, iron, and copper, and especially noting its resources of fuller’s earth which he claims is responsible for the preeminent position of the domestic wool manufactory. Also singled out for praise are resources of jet and amber, and various gemstones. The Preface closes with a summary of contents. Next appears a folding table, perhaps the most important single feature of this work because of its presentation of a scheme of classification of mineral substances which Woodward apportions among six classes, from earths to metals, and including in the second class the “durable” stones, that is, the precious gemstones, and also those gemstones that are opaque, translucent, or transparent respectively. Among the less valuable gem materials included in this section are “Stones,” e.g., alabaster, marble, ornamental rocks, nephrite, malachite, “root of the emerald” or prase, lapis lazuli, many quartz varieties, etc., with footnotes citing older authorities who describe or mention same. For the most part, this class is nearly all devoted to gemstones and rewards reading due to the abundance of interesting footnotes and asides. In the second part of the work, given its own pagination, Woodward reproduces letters written to Sir Isaac Newton and Sir John Hoskyns (1634–1705), which generally discuss classification problems and nomenclature, the second of these, and the much longer letter discussing true fossils mostly. In a third letter, commencing on p. 24, Woodward treats the “cerauniae” or, as he positively identifies them, the “stone-weapons,” about which much speculation had raged, and in the same place gives a series of engraved plates that depict examples of same. He criticizes Dr. Lister (Martin L., 1638–1712), and others, who were unshaken in their belief that cerauniae were true fossils, and even were artifacts of man grown in situ by celestial intervention. In this section Woodward also includes certain gemstones to which were ascribed magical properties, among them, British quartz pebbles, several depicted upon the first plate. Other magical stones, including some gem varieties, are also critically examined and properly identified. The remainder of the book is notable for a letter urging the systematic and scientific collecting of natural history specimens and giving in detail those precautions that should be observed in the field to insure the safety of the materials and then what steps should be taken later to preserve them. Another letter discusses belemnites and is illustrated with a plate. The importance of Woodward’s treatise is manifest; from the standpoint of the mineralogist it provides a scheme of classification of as much merit as it was possible to accrue in that time, and from the standpoints of the paleontologist and gemologist it truly identifies fossils for what they are, also figured stones to which all sorts of superstitious beliefs had been attached, and dismisses the supposed magical powers assigned to certain gemstones. One of the first mentions of corundum ('Nella Corivendum').

corundum, history.1, quality.10, gems, jade, Fischer-Book, Indian lapidary

Sinkankas: This esteemed and much sought-for work by the Parisian goldsmith is part of a metallurgical treatise in which mining and mines, methods of gold, silver, and mercury mining, purification of ores by smelting or otherwise, and refinement of metals are described. Special emphasis is laid upon the mines of the New World, and it is this that causes the work to be referenced in books in connection with the Americas. However, in the second part, which includes a short treatise with its own title page on the valuation of gemstones, we find the matter that is of greatest interest to the gemologist. This part is divided into four books, plus the valuation division mentioned, the first book treating the origin of gemstones, then describing the diamond, ruby, spinel, garnet, sapphire, topaz, emerald, amethyst, aquamarine, opal, turquoise, quartz varieties, zircon, chrysoberyl, peridot, and others that are considered to be important. The second book treats pearl and fresh-water pearls, and includes remarks on the pearls of Scotland, then much esteemed. The third book is devoted to varieties of cryptocrystalline quartz, so much so that it may be regarded as the first “agate” book to be published that deserves the name; it includes descriptions of jades, serpentine, lapis lazuli, and some other massive ornamental stones. The last book describes rock crystal, amber, and bezoars. The author apparently was well familiar with sources of gem materials because the text is quite remarkable for the detail he gives on localities. The last part of the book may be an addendum provided by Rosnel well after setting up and perhaps printing off the front matter, which, as noted before, makes no mention of it. Preceded by an inserted title leaf, and then commences page 137. It treats realistically and in detail the methods by which values are assigned to gems: diamond, ruby, garnet, and others, that is, the gems previously described in the first book. It is interesting to note that Rosnel provides a mathematical system for adjusting prices of diamonds upwards at a steepening rate with increasing weight but his method, and indeed the book itself, apparently escaped the attention of G. Lenzen, Produktions- und Handelsgeschichte des Diamanten, 1966, who paid special attention to the price structure of cut diamonds from the historical viewpoint. Rosnel’s method precedes the publication of the standard method of pricing as described by J.E. Tavernier, Les six voyages, 1676, often cited as the earliest publication of the rule, and by far anticipates the method published by David Jeffries in his Treatise, 1750.

gems, jade, Fischer-Book

Pliny’s Naturalis historia is an encyclopedic survey of the natural world compiled in the first century CE, encompassing astronomy, geography, anthropology, zoology, botany, medicine, mineralogy, and the arts. Of particular gemological importance are Books 33–37, which discuss metals, pigments, stones, and precious materials. Book 37 is devoted largely to gemstones and describes their names, appearances, reputed origins, relative values, methods of testing, imitations, engraving, and supposed medicinal or magical properties. Among the materials discussed are diamond, emerald, beryl, opal, sardonyx, amethyst, rock crystal, jasper, turquoise, and numerous other stones, making the work one of the most important surviving ancient sources for the history of gems and the gem trade. This 1469 Venice edition, printed by Johannes de Spira, was the first printed edition of the Naturalis historia and one of the earliest substantial works of classical science to appear in print.

beryl, emerald, Colombia, Chivor, gems

gems, corundum, sapphire, vesuvianite

The author recently examined a sapphire containing an elongated, rod-shaped crystal associated with a partially healed fissure (figure 8). Due to its morphology and color, the inclusion appeared to be pargasite. However, subsequent analysis using Raman spectroscopy identified the inclusion as vesuvianite. Vesuvianite is an accessory sorosilicate mineral that typically forms in skarn during metasomatism of carbonate rocks such as limestone. Exceptionally rare as an inclusion in gemstones, vesuvianite has previously only been documented in two rubies from Mogok, Myanmar (Winter 2017 G&G Micro-World, p. 469; C.P. Smith and R. Zellagui, “Vesuvianite (idocrase) and apatite inclusions in ruby identifiable by infrared spectroscopy,” Journal of Gemmology, Vol. 37, No. 4, 2020, pp. 346–348). Given the association of vesuvianite with skarns, these inclusions may also occur in sapphires from skarn deposits, such as those in Andranondambo, Madagascar, and Kataragama and Elahera, Sri Lanka (G. Giuliani and L.A. Groat, “Geology of corundum and emerald gem deposits: A review,” Winter 2019 G&G, pp. 464–489). To the author’s knowledge, this is the first report of vesuvianite as an inclusion in sapphire.

gems, gemology, gem trade, business, Asia, diamond, emerald, sapphire, Ceylon, Myanmar, pearls, Goa, Borneo, Indonesia

The “spice trade” is an essential trope in the history of maritime Asia’s role in world history, but it is less well known that precious stones often traveled along the same routes as pepper, cloves, and nutmeg. Like spices, gems were highly valued and expensive status symbols throughout the premodern world, serving as objects of spiritual and political power as well as medicines that could be worn or ingested. They were also closely associated with distinctive geographical locations across Asia (Fig. 1). Indeed, some of the most important gem-producing regions of the premodern world were located in the same parts of South and Southeast Asia that supplied the spice trade. The unique geography of gemstones not only attracted merchants from across the Indian Ocean but also drew the attention of early modern scholars seeking to understand the composition and geography of the globe.

gems, alexandrite, chrysoberyl, emerald, beryl, intergrowth, phlogopite, apatite, chalcopyrite, wurtzite, Malysheva, Russia

gems, beryl, emeralds, Austria, inclusions, micro-Raman, PL, FTIR, UV-Vis–NIR, EDXRF, LA–ICP–MS

Studies on emeralds from Habachtal (Austria) are scarce and non-exhaustive. However, they represent a significant interest to the community, as they have been assumed to be present in historical pieces of jewelry. Along with Egypt, Habachtal is suggested to be one of the main sources of gem-quality emeralds of archaeological significance. In this regard and due to their similar macroscopic look and geological context, it has always been challenging to distinguish Austrian and Egyptian emeralds set in historic jewelry. In this paper, a first comprehensive study of several Habachtal emeralds is presented based on a combination of classic gemology, chemistry, and spectroscopy, using non-destructive to micro-destructive methods. Spectroscopic analyses, such as via Raman, FTIR, and UV-Vis–NIR spectroscopies, showed that emeralds from Habachtal (Austria) contain Type II H₂O molecules with alkalis and they are colored by chromium and iron, similarly to emeralds from Egypt. Under an optical microscope (and identified by Raman spectroscopy), actinolite needle-like inclusions are frequently observed in Austrian emeralds. Other inclusions, such as quartz, plagioclase, albite, phlogopite, and pyrite, can also be observed in Austrian samples. Chemical analysis of Austrian emeralds’ trace elements by LA–ICP–MS show similar results to those from Egypt, with the exception of V, K, and Rb, which show a lesser content in Austrian emeralds. Thanks to the determination of inclusions combined with a careful examination of specific chemistry, this study shows that Austrian emeralds can be distinguished from their Egyptian counterpart.