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.

corundum, inclusions.5, gems

Sorby’s landmark paper demonstrates how microscopic examination of minerals and rocks can be used to reconstruct the conditions under which they formed. Using thin sections and transmitted-light microscopy, he studies crystal textures and, especially, microscopic cavities and fluid inclusions containing liquids, gases, and sometimes daughter crystals. Sorby shows that such inclusions may preserve samples of the fluids present during crystal growth and that changes in their liquid and vapor proportions upon heating can provide information on formation temperatures. From these observations he distinguishes minerals formed from aqueous solutions, molten material, and other geological environments and applies the method to interpreting the origin of rocks. The paper is foundational to microscopic petrography and fluid-inclusion research and is particularly important to gemology because the study of inclusions subsequently became one of the principal means of determining gemstone genesis, geological environment, and, ultimately, distinguishing natural from synthetic and treated gems.

corundum, sapphire, inclusions.5, gems

A brief note by David Brewster reporting a large fluid-filled cavity observed in a specimen of sapphire. The paper extends his earlier investigations of fluids enclosed within minerals and records the presence and behavior of the trapped liquid in corundum. Of particular gemological importance, it is an early specific description of a fluid inclusion in sapphire, demonstrating that such inclusions occur in precious stones as well as in other minerals. The notice forms part of Brewster’s pioneering work on mineral inclusions and the physical conditions under which crystals form.

corundum, inclusions.5, gems

An important early study by Humphry Davy of fluid and gaseous inclusions enclosed within crystals. Davy examines cavities containing liquid and aeriform matter in several minerals and considers the physical state, composition and behavior of the enclosed substances when the crystals are heated or broken. The paper is significant in the history of mineralogy because it helped establish that crystals can trap fluids and gases during their formation, providing evidence about the conditions under which minerals crystallize. For gemology, it is an early contribution to the study of fluid inclusions, which later became important for understanding gemstone genesis, geological environment and, in some cases, geographic origin.

gems, jade, Fischer-Book, mineralogy, early mineralogy

Very scarce. Edited by Bartolomeo Ambrosini [see note below]. Some forty years after he died, Aldrovandi's Musaeum Metallicum was published as a thick folio volume. Since his death, the work had existed as a manuscript, Geologica ovvero Fossilibus" in the library collections of the University of Bologna, which had been bequeathed all of Aldrovandi's manuscripts. Even unpublished, many scholars studied it as a resource for their own researches. The value others placed upon Aldrovandi's material did not go unnoticed, which is why a former student of the author, Bartolomeo Ambrosini was entrusted by the Bologna senate to edit the material Aldrovandi had accumulated and oversee its publication. The final product is a superb book. The work consists of a single volume divided into four books: on metals, earths, succi concreti (concrete juices), and stones (minerals, rocks, and fossils). Within each of these books, whole chapters are devoted to the consideration of a single "fossil." In a style typical of its time, each chapter then describes the fossil's medical properties, synonyms, localities, origins, varieties, and uses. Aldrovandi includes references to classical and medival authors through out the volume in a fashion that anticipated modern scholars by compiling long lists of authorities but omitting those commonly cited (Partington, 1961-70). The antiquarian nature of the book commonly gives the names and descriptions of the items listed a strange, unrecognizable character. However, Foresti (1887) attempted to ease the struggle by matching relatively modern names to Aldrovandi's. The comprehensive index included at the end of Musaeum Metallicum also makes this a reader friendly book. Perhaps the most outstanding feature for the connoiseur of mineralogic literature are the several hundered woodcuts scattered throughout the volume. Some of these are full page but most are smaller, with many possessing a quaint, interesting character. These figures are designed to illustrate features described in the text, but since minerals do not easily lend themselves to illustration, the pictures "rather require the text to explain them" (Adams, 1938). That Aldrovandi was a man of accumulation is clearly shown by his inclusion of all facts that came to his attention without apparently any critical faculty to distinguish between the true and imaginary, the important and nonessential. A great amount of scientific value is contained in Musaeum Metallicum but an overburden must be removed to discover those nuggets. In truth, the author was a product of his time. The influence of the church and other authorities did not bind his writings and ideas as they had past authors, "and so," as Adams (1938) writes, "one gathers the impression that he was writing at the opening of a new age ...""