gems, Brazil, diamond, topaz, gold, beryl, emerald, tourmaline, quartz, amethyst, Minas Gerais

Sinkankas: An outstanding and carefully researched work reflecting the author’s many years of practical experience in Brazil and involvement in the country’s mining industry. Although primarily concerned with gold, it contains an important section on gemstones (Part IV, pp. 345–446), covering diamonds, tourmaline, topaz, beryl, chrysoberyl, amethyst, euclase and other stones. It is among the earliest major works to provide a history of diamond and gemstone discoveries in Brazil, including the expeditions prompted by reports of emeralds, the subsequent discovery of diamonds, and the identification of supposed emeralds—reported from 1573 or earlier—as green tourmaline. It also describes Portuguese Crown regulations governing diamond mining and trade, reviews the diamond industry from 1749 to 1822 with production statistics, and discusses mining districts, administration, mining methods, diamond occurrences and crystal forms, specimens from the Serro do Frio in the Royal Cabinet, and the smuggling of gold and diamonds. A fundamental source for the history of Brazilian gold, diamond and gemstone mining.

gems, beryl, emerald, Egypt

Sinkankas: Jomard, the editor of the main work above, summarizes the importance of Cailliaud’s exploration in his introduction: “M. Cailliaud, favoured by a chance prize which fortune allotted him, discovered at Mount Zabarah the famous Emerald Mines, hitherto only known by passages in ancient authors, and from the recitals of the Arabs. Forgotten, as it were, during a lapse of centuries, the French voyager has retraced them, nearly in the same condition wherein the engineers of the Ptolomies left them. He has not only penetrated into subterranean cavities of a vast depth, but he has arrived at causeways, has collected tools, instruments, utensils of various kinds … [also] … he commenced the labours of the mines, and by dint of application and exertion, he is enabled to present to Mohammed Aly Pacha ten pounds of Emeralds.” The plates include a plan of the mining town of Sekket (Sikait) showing mines & buildings, a view of the town, a map of the desert region between the Nile River and the Red Sea, and several views of temples at Sikait. In addition to his descriptions of mines, ruins, etc., Cailliaud also gives an excellent mineralogy of the emerald deposits and the mode of occurrence of emerald crystals in the schistose rocks. Landmark in the history of Egyptian emerald.

gems, turquoise, turquoise identification, odontolite, Persia, Persian turquoise, Iran

An early mineralogical study by Gotthelf Fischer of two very different substances historically called turquoise. Fischer distinguishes “oriental turquoise,” which he regards as a true mineral, from “occidental turquoise” or turquoise odontolite, which he identifies as fossil tooth or bone colored by a copper compound. He proposes the name calaite for the mineral turquoise and discusses its occurrence, physical character and historical nomenclature, comparing it with Pliny’s descriptions of callais. Fischer notes that calaite occurs as rounded pieces in alluvial deposits rather than in a rocky matrix and discusses its resemblance to emerald and sapphire in ancient descriptions. The work is important in the history of gemology for its attempt to separate true mineral turquoise from odontolite and to reconcile contemporary mineralogical observations with the terminology of classical lapidary sources.

corundum, sapphire, Sri Lanka.12, India.12, chemistry.2, gems

Sinkankas: Corresponds to the first 2 vols of the German edition [of the Beiträge], and containing essays I-LXXII. In the first essay, Klaproth describes the results of subjecting numerous mineral substances to the intense heat of a porcelain fire," among them, feldspars, alabaster, marble, beryl (& emerald), tourmaline, quartzes, chrysoberyls, olivines, kyanite, opals, garnets, zircons, corundums, spinels, topazes, etc. Specific experiments and analyses on gemstones as follows: oriental sapphire, cat's-eye, chrysoberyl, chrysolite, olivine, lapis lazuli, zircon, spinel, Colombian emerald, oriental garnet, vesuvianite, leucite, staurolite, chrysoprase, Hungarian opal, hydrophane, common opals, meerschaum, Chinese agalmatolite, spessartine."

gems, history of gemology, chemical analysis, chemistry

An important methodological paper by Nicolas-Louis Vauquelin on the chemical analysis of stones and minerals, combining discussion of analytical procedures with results obtained from several mineral substances. Vauquelin considers the difficulties involved in decomposing minerals, separating their constituent earths and interpreting analytical results, illustrating the increasing reliance on chemistry for mineral identification at the end of the eighteenth century. The paper is significant to gemology because it reflects the emerging practice of distinguishing gemstones and related minerals by composition rather than by color, appearance or traditional names alone, and forms part of Vauquelin’s broader work on beryl, emerald, tourmaline, chrysolite and other gem materials.

gems, beryl, emerald, history of emerald, history of gemology, nomenclature

Emerald and beryl. I was occupied, at nearly the same time, in revising the articles relating to gemstones; and when I came to the emerald, I was struck anew by the great conformity of beryl with this substance, with regard to their hardness and specific gravity, and by the perfect identity presented by the figure and dimensions of their constituent molecules, and even by their secondary forms.¹ In truth, they had appeared to differ from one another only by refraction, which is double in the emerald, and which I had found to be simple in beryl. A very limpid prism of the latter substance had never given me more than a single image of objects, even when I viewed light placed at a distance of more than fifty toises. But recent investigations on double refraction in general led me to suspect that in every crystal possessing double refraction there exists one direction in which the image is sensibly simple, as Giovanni Battista Beccaria had already remarked concerning rock crystal. I first attempted to verify this suspicion by means of carbonate of lime, determining beforehand the manner in which one of the rhomboids known under the name Iceland spar should be cut so that, in a certain position of the eye, the two images would coincide into one. In this investigation I was guided by the knowledge acquired concerning the laws governing the double refraction of carbonate of lime, as I had explained elsewhere;² and experiment confirmed the result predicted by theory. Since analogous effects, obtained with other doubly refracting minerals, raised no doubts in my mind concerning those presented by the prism of beryl, I had a second prism cut in a different direction, and I observed that it doubled images, though only to a moderate degree; yet even in this it still approached the emerald. Thus, all the physical and geometrical characters concur in calling for the union of these two substances,³ and all that is now lacking is an analysis of beryl which, by its exactness, would deserve comparison with that which Martin Heinrich Klaproth gave for emerald, so that we may know what conclusion should be drawn from a rapprochement which mineralogy must not permit itself to make until it has obtained the consent of chemistry. The result that I have just announced will require precautions on the part of those who wish to determine whether the refraction of a mineral is simple or double. But since it seems to me that we now possess a rule for determining the direction in which only a single image is seen, it will be easy to avoid error. Theory will thereby have gained, and observation will be made more certain. ⸻ ¹ At that time beryl was known only in the form of the regular hexagonal prism, when observations made on several crystals of this gem which I had found in commerce, or had myself detached from a fragment of rock brought from Siberia, offered me a very marked rapprochement between the modifying facets on the summits of these crystals and those existing on varieties of emerald. See Journal des mines, no. XIX, p. 72. ² Mémoires de l’Académie des sciences, 1788, p. 34 ff.; Journal des Mines, Prairial, Year V. ³ Besides, the molecules here possess characters of regularity which might place them among the forms common to different substances. See Journal des mines, no. XIX, p. 72.

corundum, ruby, sapphire, history.1, India.12, quality.10, gems, Indian lapidary

An unpublished eighteenth-century manuscript devoted to precious stones, written by Matthew Gourjon in 1785 and preserved in the British Museum (Natural History). The Indian Connoisseur or The Nature of Precious Stones discusses the identification, qualities, valuation and working of gemstones from the perspective of practical connoisseurship and the gem trade. It treats a range of precious stones and includes observations on rough material, cutting, defects, color, proportions and commercial quality, reflecting the knowledge and terminology of an experienced eighteenth-century practitioner rather than a purely academic mineralogist. The manuscript is particularly valuable as a rare primary source for contemporary methods of judging and handling gemstones and for the history of gem cutting and commerce in the later eighteenth century. Gourjon understood that the oriental ruby, oriental sapphire, oriental emerald, oriental amethyst, etc. were all the same type of gem (corundum) over a decade before Count de Bournon formally defined the species.

gems, gemology, general gemology, France, jewelry, diamond, ruby, spinel, topaz, sapphire, emerald, “prime d’émeraude,” amethyst, aquamarine, opal, garnets, zircon, peridot, turquoise, pearl, coral, amber, jet, strass, agate, sardonyx, carnelian, jade, bloodstone, chalcedony, lapis lazuli, rock crystal, fluorite, marcasite, alabaster, porphyry, marble

Sinkankas: An extremely important work which is esteemed for its accurate statement of the everyday knowledge possessed by jewelers and experts in gems in France of the 18th century but perhaps even more highly valued for its many hundreds of carefully drawn and engraved jewelry designs which appear upon the plates. Apparently these were designed by Pouget, the noted Parisian jeweler, and engraved on copper by Mademoiselle Raimbau whose name appears upon the first plate. No less than 30 types of jewelry are listed in the text, including 6 orders of chivalry and various large and ornate “bouquets.” The work begins with a preface that extols the arts of the jeweler, especially as practised in France, and then gives a lengthy poem on the discovery of fire, and passes to a listing of jewel-gems in two categories of esteem, with a list of other lesser-valued gemstones. There are also lists of gemstones in the High Priest’s breastplate and the stones assigned to zodiacal signs, plus a short historical note on the uses of gems. The descriptive text takes up diamond, ruby, spinel, topaz, sapphire, emerald, “prime d’émeraude,” amethyst, aquamarine, opal, garnets, zircon, peridot, turquoise, pearl, coral, amber, jet, strass, agate, sardonyx, carnelian, jade, bloodstone, various chalcedonic quartzes, lapis lazuli, rock crystal, fluorite, marcasite, alabaster, porphyry, and marbles. Other gemstones are occasionally included under the above headings, but sometimes misleadingly as in the case of “oriental” topaz, a sapphire, described along with the genuine topaz. Following this large and important section, Pouget furnishes descriptions of the metals employed in jewelry, including copper, iron, tin, lead, mercury, and the lodestone. An interesting group of small woodcuts depicting the Grand Mogul, Duke of Tuscany, Sancy, and Regent diamonds appear in the diamond discussion and are among the earliest such pictorial representations to be found in the gemological literature.

gems, jade, Fischer-Book

Very scarce. First and only edition of this magnificent work, which is a summation of all that was worth knowing at the time of minerals and gemstones. Adams considered it a guide book to the maze of ancient literature of the geological sciences. It is divided into six books. The first describes gemstones and their precious nature together with extensive references. Other discussions include color, phosphoresence, luminescence, virutes, pricing and fake gemstones. The second book considers the precious stones like diamond, emerald, sapphire, ruby and others. The third describes stones of lesser value and the fourth discusses stones derived from organic sources such as calculi, boazoar and other like stones. The fifth book describes marbles, mosaics, pietre dure inlays and many other similar examples. The sixth book is largely on earths of various kinds.

gems, corundum, History.1, diamond, beryl, emerald, sapphire, ruby, topaz, quartz, spinel, garnet

Sinkankas: In this early Spanish work, Mosquera deals with the theoretical & practical aspects of weighing and valuing precious stones, but supplies much highly interesting ancillary information. There are eight books, the first & second on diamond, third on rubies, fourth on emeralds, fifth on sapphires & topazes, sixth on amethysts, spinels, garnets, among others, seventh on pearls, and the last book comprising miscellaneous information on the stones and pearl previously treated. The instructions show readers how geometrical principles may be used to accurately estimate weights of cut gems that otherwise could not be handled singly, e.g., as gems in mountings. Mosquera also tells how to correctly judge cutting proportions and thus aid in arriving at more accurate estimates of value, here referring the reader to the folding engraved plate which shows geometric diagrams based on the octahedral crystal of natural diamond, its cross-section, various geometrical forms, diagrams of several cut gems, a balance with weights, scales for measurement, etc., all aimed at facilitating weight estimation, correct cutting proportions, and values. Many tables of weight vs style of cut are incorporated in the text with much of the information similar to that given by Jeffries in his A Treatise on Diamonds and Pearls, 1750, which see, and which may have been consulted by Jeffries, although we have no sign that Jeffries even knew of the existence of Mosquera’s book. A rare work.