corundum, inclusions.5, Burma.12, Sri Lanka.12, Thailand.12, gems

Escard provides a concise survey of the ruby, describing its varieties, physical properties, geographical sources, mining, cutting, valuation, and methods of distinguishing natural stones from imitations and artificial products. [655] He identifies ruby as red corundum and discusses differences in color among rubies from Burma, Siam, and Ceylon, noting that terminology such as “Oriental ruby” and “Siam ruby” was often applied inconsistently in commerce. [656] Particular attention is given to microscopic examination: natural rubies may contain crystalline inclusions and other internal features, while differences in color and dichroism can help separate stones from different sources; illustrations show characteristic inclusions and a Ceylonese lapidary at work. [657] Escard discusses the distinctive internal structure of Burmese and Siamese rubies, differences observed with the dichroscope, and variations in specific gravity, accompanied by photomicrographs and a map of the ruby-bearing district of Burma. [658] Fluorescence and phosphorescence are described as useful diagnostic properties, Burmese rubies showing particularly strong fluorescence; the principal ruby deposits are said to occur in Burma and Ceylon, where ruby-bearing gravels are washed and sorted, with an account of mining and recovery methods in the Mogok district and illustrations of the Burmese mines. [659] The article gives production and value figures for Burmese ruby mining, mentions occurrences in Ceylon, Siam, Afghanistan, and elsewhere, discusses the considerable variation in value according to color, quality, and size, and briefly describes cutting practices, including the preference for the oval form. [660] Escard concludes with remarks on celebrated rubies, including stones associated with European collections, and emphasizes the commercial importance of distinguishing natural rubies from artificial stones, illustrating a certificate of authenticity for a natural Burmese ruby.

corundum, synthetic corundum.7, gems

Heaton reviews the contemporary production of artificial precious stones and the methods available for distinguishing them from their natural counterparts. Particular attention is given to synthetic ruby and sapphire, including the processes developed by Frémy and Verneuil, the materials and apparatus employed, and the physical and optical properties of the resulting products. The paper discusses the identification of artificial stones by microscopic examination, inclusions, internal structure, and other diagnostic characteristics, and considers imitation and reconstructed stones alongside true synthetic products. Published at a time when flame-fusion corundum was becoming commercially important, it provides a useful contemporary account of the problems that synthetic gemstones posed for jewelers and gemologists.

gems, corundum, inclusions.5, synthetic.7

Small booklet describing how to separate natural rubies from the newly developed synthetic rubies.

corundum, USA.12, North Carolina.12, Montana.12, gems

Kunz reviews the precious-stone industry and trade in 1887, beginning with American gem mining and estimated U.S. production, then describing recent discoveries and developments involving diamond, zircon, beryl, phenacite, garnet, tourmaline, hiddenite, rock crystal, chrysoprase, agate, pectolite, feldspars, rhodonite, turquoise, cyanite, labradorite, and ornamental stones. Kunz-1888-Precious stones.pdf A substantial section treats foreign sources, particularly the rapidly expanding South African diamond mines, their mining and sorting methods, production, values, consolidation, and effects on the international diamond trade; Kunz also discusses Brazilian, Indian, and Australian diamond production and the growth of diamond imports, cutting, and consumption in the United States. Of particular gemological interest are detailed accounts of the Kashmir sapphire deposit, discovered in 1882 in the Zanskar Range, and the Mogok ruby mines of Burma, including British attempts to lease the mines, contemporary mining practices, royalties, and trade. Kunz also surveys changing fashions in gems, including cat’s-eye, alexandrite, moonstone, opal, and amber, and notes the rapidly growing American interest in carved jade and other hardstone objects. He discusses Alaskan jade, Central American jadeite artifacts, Burmese jadeite, and Māori jade objects, while recording contemporary theories concerning the provenance of American jadeite. The report concludes with accounts of important gem collections and their dispersal or acquisition, including the Hope collection, the French Crown jewels, C.W. King’s engraved gems, the Sommerville collection, W. Hayes Ward’s ancient cylinders, and Isaac Lea’s collection of gems studied for microscopic inclusions.

corundum, inclusions.5, gems

A detailed continuation of Isaac Lea’s earlier studies of microscopic inclusions in gemstones and minerals. Drawing on an enlarged personal collection, Lea examines cavities, fluid inclusions and minute enclosed crystals in sapphire, ruby, spinel, emerald, beryl, zircon, moonstone and other gem materials. Of particular importance is his observation that fine sapphires commonly contain abundant acicular crystals and cavities; he relates the oriented needles directly to the intersecting bands that produce the star in asteriated corundum. He also describes inclusions in North Carolina corundum, Ceylon sapphires and spinels, emeralds containing fluid-filled cavities with enclosed cubic crystals, and other distinctive internal features, illustrating many of them on two plates. The paper is an important early contribution to gemstone microscopy and to the recognition of inclusions as diagnostic evidence of a gem’s internal structure and growth history.

gems, jade, Fischer-Book

Fischer presents the first continuation of his critical microscopic-mineralogical studies, applying microscopic examination to the identification and differentiation of minerals and rocks whose true nature could be difficult to establish from external appearance alone. He compares microscopic structure, texture, inclusions, and other diagnostic characteristics with chemical and physical evidence and critically reassesses earlier mineral identifications. Of particular relevance to jade research are the discussions on pp. 9, 24–25, and 48, where nephrite and related or superficially similar materials are considered as part of Fischer’s continuing effort to distinguish true nephrite from “pseudonephrite” and other jade-like substances. The work illustrates the increasing importance Fischer attached to microscopy in resolving the nineteenth-century “jade question” and in establishing more reliable mineralogical identifications of archaeological stone artifacts.

corundum, inclusions.5, ruby, sapphire, spinel, aquamarine, beryl, emerald, gems

Sorby and Butler investigate the internal structure of rubies, sapphires, diamonds, and other minerals by microscopic examination, using inclusions and growth features to interpret the conditions under which the crystals formed. They describe minute cavities, enclosed crystals, and structural irregularities visible within transparent specimens and compare their character and distribution in different minerals. Particular attention is given to rubies and sapphires, whose internal features provide evidence of successive stages of crystal growth, and to diamonds, in which inclusions and structural characteristics are likewise examined. The authors argue that microscopic features preserved within crystals can provide important evidence concerning their origin and formation. The paper is an important early contribution to the systematic microscopy of gemstones and helped establish the study of inclusions and internal growth structures as a means of investigating mineral genesis.

corundum, inclusions.5, gems, inclusions, history of microscopy

Lea reports microscopic observations of minute crystals enclosed within larger mineral specimens, emphasizing that such inclusions may themselves possess recognizable crystalline forms and provide evidence concerning the formation of their host minerals. He describes microscopic crystals observed in several minerals and considers their shapes, arrangement, and possible mineralogical identity. Of particular gemological importance is the early application of microscopy to the study of inclusions in transparent minerals, demonstrating that internal features could reveal information not obtainable from external examination alone. The paper anticipates the later systematic use of inclusions in gemology for mineral identification and for interpreting the conditions and sequence of crystal growth.

corundum, ruby, sapphire, history.1, quality, gems, glyptic

Sinkankas: This volume is primarily a comprehensive history of the art of gem engraving, enriched with additional material that amplifies or embellishes the central theme. The opening chapter—an extensive 183 pages—is historical in nature, followed by chapters on famous rings and signets, European cabinets of engraved gems, artists' signatures, a catalog of ancient gem engravers, and a curious inclusion: a lengthy ode to the bronze statues in the Gymnasium of Zeuxippus by a certain Christodorus, inserted without a clearly discernible purpose. Subsequent chapters describe the gems illustrated in the plates and elsewhere, concluding with a chapter of detailed notes. Written in King’s meticulous and richly detailed style, the work, like his earlier publications, is a treasure trove of information, particularly valuable today for its descriptions of contemporary gem collections, which now hold significant historical importance. Many surviving copies suffer from weak, embrittled cloth—especially along the spine—and intact, sound copies are rare.

gems, inclusions, microscopy, aesthetics, photomicrography, art

Manufacturing experience affords many instances of surprising success achieved by ornamental goods, whose patterns were judiciously selected from natural objects; but although examples of various combinations of form and colour occur in great profusion in those portions of the natural world which are accessible to unassisted sight, the microscope constantly presents us with a rich store of ideas which the decorative artist would do well to study and employ. If colour be the especial subject of his pursuit, the wings of butterflies or the wing-cases of beetles, the petals of flowers—such as London-pride—minute sea-weeds, and other common objects, are highly instructive; and if we were requested to point out an illustration of the union of extraordinary splendour with grateful repose, we could not do better than refer to the armour in which the diamond beetle is arrayed. When Mr. Owen Jones completed his Alhambra Court, at the Crystal Palace, every one was struck by the mingled softness and gorgeousness of the aspect. The eye could look steadily without being wearied, while a visit to the House of Lords, when its colours were new and fresh, afflicted observers with an unpleasant sense of tension, rapidly followed by weariness, from which there was no escape. Even in the cases of persons afflicted with colour blindness, we sometimes find that what may be called colour discords are productive of disagreeable impressions, while colour harmonies, although only partially perceived, call forth pleasurable emotions. Still more striking are the effects of colour harmonies and discords upon individuals whose physical and mental organs are in a sound and cultivated state. They are not satisfied with the mere avoidance of mistakes, or with the presentation of the most elementary concords which pigments can produce. Their tastes lead them to desire to untwist all the chains of colour harmony; they love the complicated effects of tertiary combinations, and are discontented with brilliance if it be destitute of repose.