corundum, ruby, sapphire, inclusions.5, Kashmir.11, India.12, gems

Gübelin reviews the diagnostic value of gemstone inclusions and their significance for understanding mineral formation. Improved dark-field binocular microscopy permits examination of inclusions throughout a faceted stone, revealing characteristic differences in their composition, form, orientation, and distribution. Inclusions are classified both by their timing relative to host-crystal growth and as solid, liquid, or gaseous components. Examples from diamond, corundum, beryl, garnet, tourmaline, spinel, moonstone, and fluorite illustrate their use in gemstone identification and, in some cases, determining geographical origin. Particular attention is given to locality-specific inclusion assemblages in rubies and sapphires, three-phase inclusions in emeralds, and characteristic mineral inclusions in garnets. The paper emphasizes that diagnostic value frequently resides in the overall inclusion pattern and its relationship to crystal structure, rather than in an isolated inclusion. Five plates illustrate representative features. Gübelin advocates closer collaboration between gemmology and mineralogy to advance both practical identification and interpretation of crystal growth.

corundum, color.4, gems

Spectrochemical and spectrophotometric investigations of natural and synthetic rubies and sapphires were undertaken to compare their compositions and optical properties and explore possible methods of distinguishing them. For spectrochemical analysis, ruby samples were ground in a boron carbide mortar under acetone to minimise contamination and examined using the Harvey method of semiquantitative analysis. Results for two natural and two synthetic rubies, comprising a light and a dark specimen of each, were expressed as oxide percentages. Alumina constituted 96.5–98.8% of the samples, while chromium oxide ranged from 0.945 to 2.58%, with higher concentrations in the darker specimen of each pair. Silica and minor quantities of copper, cadmium, magnesium, molybdenum and iron were reported in all four specimens. Vanadium was detected in both natural rubies but in neither synthetic ruby. Numerous additional elements, including titanium, were sought but not detected in these four samples. Separate analyses examined the clear core, combined core and outer layers, and outer layers alone of a Linde synthetic star ruby to investigate the material producing asterism. Titanium increased from 0.064% in the core to 0.162% in the outer layers containing dense interlocking crystals. This enrichment supported the suggested identification of the star-producing inclusions as titania, consistent with their microscopic resemblance to rutile needles in natural rubies. Magnesium was also more abundant in the outer layers, whereas chromium concentrations were relatively similar throughout the analysed sections. Spectrophotometric measurements were made with a Hardy recording spectrophotometer on highly polished plates of natural and synthetic ruby and sapphire measuring approximately 2 mm square and 1 mm thick. Visible spectral reflection curves showed broadly similar patterns for natural and synthetic examples of each gem variety, in keeping with their closely comparable chemical and physical properties. Ruby curves exhibited a broad blue-region maximum, a yellow-region minimum and a pronounced rise towards red wavelengths; sapphire curves showed a broad blue-region maximum followed by lower reflection at longer wavelengths. The curves were submitted to Eastman Kodak for investigation of a special filter that might permit rapid differentiation of natural and synthetic corundum. Research remained incomplete, and no wholly satisfactory filter had been obtained.

travel and exploration, India, diamonds, Golconda, gems

The Travels of the Abbé Carré in India and the Near East, 1672 to 1674 is an English translation of the manuscript journal of Barthélemy Carré, a French Catholic priest and traveler whose journeys provide a detailed account of political conditions, commerce, religion, and European colonial rivalry in seventeenth-century India and the Near East. Translated by Lady Fawcett and edited by Sir Charles Fawcett with the assistance of Sir Richard Burn, the work was published by the Hakluyt Society in three volumes between 1947 and 1948. Carré traveled extensively through the territories of the Mughal Empire, the Deccan sultanates, and European trading settlements, recording his experiences and observations of local rulers, merchants, religious communities, transportation, and commercial practices. His narrative is particularly valuable for its contemporary descriptions of the French East India Company’s early attempts to establish itself in India and the fierce competition among French, Dutch, English, and Portuguese interests. The second volume concentrates on Carré’s journey from Bijapur through Golconda and Bhagnagar (Hyderabad) to the Coromandel coast in 1673, followed by his account of French military operations at St. Thomé, near Madras (Chennai), and the conflict involving the kingdom of Golconda and the Dutch. Of particular gemological interest is Carré’s description of the opulent court of Golconda, whose princes and nobles displayed their wealth through jewels and precious stones adorning their persons, elephants, horse harnesses, weapons, and palanquins. He describes the fortified royal city of Golconda and neighboring Bhagnagar as centers of extraordinary wealth and commerce, attracting merchants from many countries. Although Golconda was internationally renowned for its diamond trade and the celebrated diamond-producing districts associated with its kingdom, Carré’s account in this volume emphasizes the visible wealth of the court and the commercial importance of the region rather than providing detailed descriptions of diamond mining or cutting. In discussing the ambitions of the French East India Company, he specifically identifies pearls and diamonds among the valuable commodities that European merchants sought to obtain, alongside spices, textiles, and other luxury merchandise. His descriptions of the Dutch trading establishment at Bhagnagar, its warehouses, commercial privileges, customs arrangements, and extensive trading networks offer valuable evidence of the organization of European commerce in this important Indian market. The narrative also records the movement of merchants and merchandise between Golconda, Surat, Masulipatam, Madras, Ceylon (Sri Lanka), and Southeast Asia, illustrating the commercial connections through which precious stones and other luxury goods could circulate. Carré’s strong French patriotism, religious prejudices, and occasional exaggerations require critical interpretation, a problem addressed in the editors’ extensive historical annotations. The work is an important primary source for the economic and political history of seventeenth-century India, particularly the commercial environment surrounding Golconda during the period of its greatest international reputation as a center of the diamond trade.

synthetic corundum.7, gems

This digest, based on a report in the January 1947 issue of Watchmaker, Jeweller & Silversmith, summarizes German wartime production of synthetic sapphire and spinel, giving particulars of manufacturing capacity, operating conditions, product quality, and an adaptation for industrial use. Two factories are identified: the I.G. Farben plant at Bitterfeld and the Wiedes Karbid Werke at Freyung. Both employed the basic Verneuil process to produce boules. The Freyung installation had 204 burners and a stated capacity of 60,000 carats daily, while the Bitterfeld factory had approximately 300 burners and a somewhat greater capacity. At the time described, aquamarine-colored synthetic spinel accounted for 90 percent of the Wiedes plant’s production. The operating data indicate boule weights of 150–200 carats, growth periods of four to five hours, and cooling periods of half an hour to one hour in the furnace. Powder tapping occurred at a frequency of 60–80 times per minute. Hydrogen consumption was reported as four cubic meters per hour, with a hydrogen-to-oxygen ratio stated as 2:3, and overall powder utilization of 60 percent. These figures accompany a breakdown of production quality: under normal operating conditions, 60 percent of the boules were classified as first quality, 20 percent as second quality, and 20 percent as third quality. The report therefore records both the scale of manufacture and the distribution of its output among commercial grades. Particular attention is given to wartime work by Wilhelm Epler, collaborating with Albert Maucher and Drescher Kaden. A serious shortage of diamond powder prompted them to develop a method for hardening the surfaces of synthetic spinel jewel bearings after the bearings had been fashioned. The resulting bearings could be worked with carborundum powder, whereas corundum required diamond powder. The digest presents this as the most interesting wartime development in the German synthetic industry. It closes by stating that no evidence had been found that the German factories had developed synthetic corundum or spinel in rod form comparable to material being manufactured in the United States.

synthetic corundum.7, gems

This three-part series reviews methods available in 1946–1947 for distinguishing synthetic corundum, spinel, and emerald from their natural counterparts, emphasizing microscopic examination of inclusions and growth structures. R.T. Liddicoat introduces the distinction between a synthetic gem, which reproduces the chemical composition and atomic structure of its natural counterpart, and an imitation marketed under an inaccurate name. Materials sold as synthetic alexandrite, zircon, garnet, or aquamarine are described as corundum or spinel substitutes identifiable by their different properties. For natural and synthetic corundum, however, ordinary refractive-index and density measurements provide little assistance, making internal features particularly important. Natural ruby and sapphire are illustrated by fingerprintlike fluid inclusions, zircon crystals with surrounding fractures, oriented silk intersecting at 60°, and straight or hexagonally arranged growth zoning. Synthetic material produced by the Verneuil process is characterized by spherical or elongated gas bubbles and curved growth striae. The authors explain that nearly flawless specimens require higher magnification, careful control of illumination, examination from different directions, and sometimes immersion to reduce distracting surface reflections. E.J. Gübelin expands the discussion of gas inclusions, describing isolated bubbles, localized clouds, and concentrations following growth layers, while noting that improvements in production reduce their abundance and size. He cautions that subsurface cracks caused by rapid polishing occur in both natural and synthetic corundum and therefore do not establish synthetic origin. The third installment treats synthetic spinel separately because curved striae are absent from the material examined. Its gas inclusions may be spherical, tubular, wormlike, or irregularly elongated, while characteristic strain patterns under crossed polarizers provide further evidence. Gübelin contrasts the cloudy, fibrous, or feathery anomalous birefringence of synthetic spinel with the generally fainter, less sharply defined patterns observed in natural specimens. Synthetic emerald presents a different problem because its slower crystallization can produce straight or hexagonal zoning resembling natural growth. Slightly lower refractive index, density, and birefringence are discussed as supporting distinctions, but microscopic features receive greater practical emphasis. These include scattered minute solid particles, undulating wisps or feathers described as groups of small liquid inclusions containing gas bubbles, irregular cavities, and pronounced strain-related anomalous birefringence. Gübelin treats the identity of the scattered solid particles as uncertain, tentatively suggesting coloring material. Recommended observation methods include dark-field microscopy, transmitted light, crossed polarizers, and immersion, with the lighting selected to reveal particular structures. Spectroscopy and luminescence are mentioned as supplementary approaches when microscopy proves insufficient. Throughout, the series presents identification as a matter of recognizing diagnostic internal features while avoiding conclusions based on ambiguous cracks, superficial resemblance, or the absence of conspicuous imperfections.

gem testing laboratory, instruments, gems

This two-page presentation documents the equipment and arrangement of the Gübelin gemological laboratory in Lucerne, Switzerland, through descriptions of its left and right sections. The laboratory is identified as a spacious, well-equipped facility within the E. Gübelin store, complemented by a smaller but complete laboratory in Gübelin’s home. Both are described as settings for his gemological research. The account provides an inventory of instruments rather than reporting a particular investigation, experimental procedure, or set of analytical results. In the left section, the equipment is listed in sequence as a pearl endoscope, pearloscope, pearl fluorescence apparatus adapted from a pearl compass, absorption spectrometer, polarizing microscope, horizontal gemological microscope, and polariscope. This combination places specialized pearl examination alongside spectroscopy and microscopic observation. The right section contains a small gemoscope, ultraviolet lamp, Gemmolux, Zeiss refractometer with a sodium discharge lamp, Rayner refractometer, streak plate, hardness pencils, detectoscope, dichroscope, hydrostatic balance, density liquids, liquids for surface testing, and Newton scales. Gem tables are also noted on the wall at the extreme left. The inventory brings together several complementary approaches to gemstone examination: magnification, observation with polarized light, absorption spectroscopy, fluorescence testing, refractive-index measurement, dichroscopic observation, density determination, and tests involving hardness, streak, and surface properties. The inclusion of both a hydrostatic balance and density liquids records provision for different methods of investigating density, while the two refractometers document the availability of instruments from different manufacturers. Pearl-testing apparatus forms a distinct part of the equipment, demonstrating that the laboratory’s scope extended beyond the examination of transparent colored stones. By specifying the instruments in their physical order, the accompanying descriptions connect individual items with the laboratory’s overall arrangement. The presentation thus records the range of tools available to Gübelin in 1946 and the coexistence of specialized optical apparatus with conventional physical testing equipment. Its principal contribution is a contemporary description of the facilities supporting his gemological work, rather than an explanation of how each instrument was operated or evidence of the results obtained with it.

fiction, moonstone, gems

Wilkie Collins’s The Moonstone, first published in 1868, is a pioneering English detective novel centered on the theft of a magnificent yellow diamond and the mystery surrounding its disappearance. The story begins during the British assault on Seringapatam (Srirangapatna), India, in 1799, when Colonel John Herncastle acquires a celebrated diamond under circumstances suggesting murder and plunder. According to the fictional history recounted in the novel, the diamond originally adorned the forehead of a Hindu moon deity and was guarded for centuries by hereditary Brahmin priests. Its name, the Moonstone, derives from its unusual yellow color and the belief that its brilliance waxes and wanes with the phases of the moon. Collins carefully distinguishes this diamond from the semitransparent gemstone moonstone, which was likewise associated in ancient European traditions with lunar influences. The diamond’s history encompasses the temples of Somnath and Benares (Varanasi), successive military conquests, and the determination of its religious guardians to preserve or recover the sacred jewel. Herncastle eventually bequeaths the diamond to his niece, Rachel Verinder, who receives it on her eighteenth birthday at her family’s Yorkshire estate. When the gem disappears from her bedroom that night, suspicion falls upon several members of the household and a group of Indian visitors believed to be searching for the stone. Sergeant Cuff, a celebrated detective, is called upon to investigate, but the circumstances surrounding the theft prove unusually complicated. The narrative unfolds through the testimony of several characters, each offering a different perspective on the mystery and revealing the prejudices, assumptions, and personal interests that influence their accounts. Of particular gemological interest are the descriptions of the diamond’s remarkable size, yellow color, supposed supernatural properties, and considerable monetary value. Collins also introduces the commercial realities of the nineteenth-century diamond trade, including valuation, the significance of flaws, and the possibility of recutting a large, recognizable diamond into smaller stones to facilitate its disposal. The contrast between the diamond’s enormous financial value in England and its sacred significance in India provides an important underlying theme. The novel also reflects contemporary European fascination with famous Indian diamonds, particularly those associated with royal treasuries, warfare, and colonial acquisition. Although the Moonstone itself is fictional, its history evokes the complicated movements of celebrated gems between Indian rulers and European collectors. Beyond its gemological interest, the novel is notable for its sophisticated construction, distinctive narrators, psychological observations, and early use of investigative techniques that subsequently became conventions of detective fiction. The Moonstone remains a significant literary treatment of gemstones as objects of wealth, religious devotion, political power, and personal obsession, while offering a revealing perspective on nineteenth-century British attitudes toward India and its precious stones.

gems, general gemology, precious stones

An introductory manual of gem identification for students and practising jewellers, this American revision of Robert Webster’s Practical Gemmology combines elementary scientific explanation with descriptions of testing instruments and concise reference accounts of gem materials. Virginia V. Hinton’s revisions adapt the work to American practice, adding information on equipment, terminology and commercial standards. The opening chapters introduce the qualities underlying gem value and distinguish minerals, rocks, crystals, crystalline aggregates and amorphous substances. Elementary crystallography explains crystal systems, symmetry, axes and twinning, relating internal structure to optical behaviour, identification and cutting. Physical properties include cleavage, fracture, hardness and lustre, followed by detailed treatment of specific gravity and its determination through hydrostatic weighing, heavy liquids and other methods. The optical chapters explain reflection, refraction, total internal reflection, dispersion, polarisation and double refraction before describing refractometers and alternative methods of measuring refractive index. Colour is treated as an aid requiring confirmation by instrumental testing, with discussions of pleochroism, dichroscopes, absorption spectra, colour filters, fluorescence and phosphorescence. A chapter on microscopy covers magnification, illumination and the examination of features useful in identifying gems and their substitutes. The principal gem species are then summarised through chemical composition, crystallography, diagnostic constants, appearance, varieties and geographical occurrence. Expanded diamond coverage discusses inclusions and surface blemishes, cutting proportions, the meaning of flawless, and the importance of standard magnification and controlled lighting in clarity and colour assessment. Subsequent chapters distinguish synthetic gems from imitations, describe their production and recognition, and examine glass, plastics, assembled stones and artificially induced colour. Cutting styles are explained in relation to the appearance and optical properties of fashioned stones. Organic materials receive separate treatment, especially pearls, their formation, cultivation, imitations and methods of distinguishing cultured from natural examples. Coral, amber, jet, tortoiseshell and ivory are also described, followed by unusual gem species and ornamental, decorative and curio stones. Diagrams, photographs, tables of constants, chapter recapitulations, test questions and answers support instruction and reference use. The emphasis throughout is on accessible principles and practical discrimination, with more intricate scientific tests deliberately left to advanced works.

gems, jade, bibliography, books on books, auction catalog

The Yamanaka Library on Far Eastern Art is an auction catalogue documenting the reference library of Yamanaka & Company, one of the most influential international dealers in Chinese and Japanese art during the late nineteenth and early twentieth centuries. Published by Parke-Bernet Galleries in New York as Sale No. 576, the catalogue was prepared for a public auction held on June 6–7, 1944, by order of the Alien Property Custodian of the United States, following the seizure of the American assets of the Japanese-owned firm during the Second World War. The library had been assembled for the use of Yamanaka’s New York and Boston establishments and contained specialized publications relating to Chinese and Japanese art, archaeology, craftsmanship, and collecting. Its contents included books on jade, lacquer, ceramics, porcelain, bronze vessels, sculpture, painting, prints, and other decorative arts, together with exhibition catalogues, publications issued by Yamanaka & Company, and works on Japanese flower arrangement. The collection reflects the scholarly resources available to a major international art dealership whose activities helped shape Western appreciation and collecting of East Asian antiquities. Particularly important for the history of jade are the publications devoted to Chinese carved hardstones, ancient ritual objects, imperial collections, archaeological discoveries, and the classification and interpretation of jade artifacts. Such works were essential references for dealers and collectors attempting to establish the age, authenticity, artistic significance, and value of Chinese jades. The library also documents the importance of illustrated catalogues, museum publications, and specialist monographs in disseminating knowledge of East Asian art to Western audiences. The inclusion of Chinese bronzes, ceramics, and other antiquities provides a broader context for understanding how jade was studied alongside related categories of Chinese material culture. Beyond its bibliographic value, the catalogue is significant as a record of the dispersal of an important commercial reference library during wartime. The forced liquidation of Yamanaka’s American holdings formed part of a wider series of auctions involving the firm's art collections and commercial stock. These sales marked a major disruption in the international trade in East Asian art and dispersed objects and scholarly resources accumulated through decades of collecting and dealing. For historians of gemology, art collecting, and the antiquarian book trade, the catalogue provides evidence of the literature used by one of the principal dealers in Chinese jade and other Asian works of art. It is also potentially useful for identifying rare publications, tracing bibliographic editions, and reconstructing the scholarly foundations of early twentieth-century Western connoisseurship of Chinese and Japanese art. Although the complete catalogue has not been examined, its documented scope and provenance establish its importance as a historical record of a specialized art reference library and the international trade in East Asian antiquities.

gemology, organic gems, coral