gems, beryl, emerald, Colombia, inclusions

Emeralds from the district Somondoco (Colombia) were analyzed by electron microprobe, colorimetry (Be), emission spectrography (Li), and thermogravimetry and infrared absorption (H₂O). They typically show the following atomic substitutions (per 18 oxygens): 0.13–0.21 Al in the SiO₄ tetrahedra, 0.14–0.40 for the sum of Cr, V, Fe, Mg in the AlO₆ octahedra, and 0.02–0.06 Li plus 0.00–0.170 in the BeO₄ tetrahedra; the “channel” alkalis, mostly Na, total 0.13–0.29. Fluid inclusions in these emeralds contain liquid H₂O, liquid CO₂, daughter crystals of halite and calcite (?), and liquid and gaseous hydrocarbons. The behaviour of the fluid inclusions on freezing and heating and their frequent decrepitation, stretching, and leaking are described. Temperatures of homogenization (Th) values are ≥ 470 °C, but only those close to the lower limit seem unaffected by inclusion stretching, etc. A roughly estimated pressure (≤ 1 kbar) would require a pressure correction of about 100 °C to the Th values. The total salt concentration in fluid inclusions is close to 40 wt.%, and the dissolved salt composition inferred from the electron microprobe analyses of the precipitates from decrepitated inclusions is probably: Cl, Na > Ca, Si, Al, (C) > Fe, K, Mg > Mn, Ti. The behaviour of other possible components in the mineral-forming process is also discussed. It is calculated that beryllium fixed in emeralds makes up only 0.2 to 1 wt.% of the total Be in the emerald-bearing rocks and veins. The proposed model of the origin of emeralds involves only components mobilized from the country rocks, without recourse to a deep-seated or magmatic source.

synthetic beryl, emerald, gems

Thirteen faceted Russian hydrothermal synthetic emeralds are characterized through chemical analysis, physical measurements, polarized absorption spectroscopy, infrared spectroscopy, and microscopic examination, with comparisons to natural emeralds and published Russian synthesis research. The specimens range from 0.35 to 2.34 ct and include commercial material and a sample obtained from the Novosibirsk research institute. Their unusual composition combines low magnesium and sodium contents with substantial chromium, iron, nickel, and copper. These transition elements raise refractive indices and specific gravity, partly offsetting the effects of low alkali contents and producing values within the natural emerald range. Ordinary refractive indices are 1.580–1.586, extraordinary indices 1.573–1.579, birefringence 0.006–0.007, and specific gravity 2.68–2.70 for specimens without seed remnants. All samples are inert to long-wave and short-wave ultraviolet radiation, consistent with iron quenching chromium fluorescence. Polarized spectra indicate that chromium and nickel dominate color and pleochroism, with subordinate contributions from iron and copper. Pleochroism ranges from greenish blue to blue parallel to the optic axis and yellow-green to greenish yellow perpendicular to it. This appearance resembles certain natural emeralds but arises from different absorption mechanisms; earlier interpretations invoking an aquamarine component are rejected for the examined material. Infrared spectra reveal both type-I and type-II channel water, demonstrating that their coexistence cannot establish natural origin. Type-II water is attributed principally to association with lithium because sodium concentrations are very low. Microscopy reveals colorless beryl seed remnants in six specimens and growth zoning inclined approximately 31° to the optic axis throughout the sample group. Step-like zoning, cobbled seed boundaries, and characteristic blocks of subparallel crystal subindividuals provide particularly valuable diagnostic features. Inclusions include opaque platelets considered more likely hematite than platinum, birefringent crystals associated with fluid-filled growth tubes, and feathers containing liquid, two-phase, and three-phase inclusions. Some stones contain little foreign material, making growth structures especially important. The observed features are related to growth on specially oriented beryl seeds in steel autoclaves without precious-metal liners. Published industrial conditions include temperatures of 550–620 °C and pressures near 1,000 bar; autoclave corrosion and deliberate additions are considered possible sources of incorporated metals. The study concludes that trace-element composition, polarized ultraviolet-visible spectra, and immersion microscopy together provide effective recognition criteria, despite overlap with natural emeralds in routine physical properties and infrared water spectra.

emeralds, gold, spanish treasure, treasure hunting, Mel Fisher, gems

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

Catalog of an exhibit on Indian jewelry curated by Elisabeth Markevich.

gems, corundum, quality.10, crown jewels, auction, diamond, pearl, jade, beryl, emerald

This mid 1980s book is a portrait of a number of Indian princes and their sumptous lifestyle. An account of the Princes of India, who lived lives of fabled splendour until, in the early 1970s, Prime Minister Mrs. Gandhi removed their titles. Later, the Maharajahs became ambassadors and politicians, many of their palaces have become hotels, but their legend is part of India.

corundum, beryl, emerald, history.1,, gems

The aim of the author was to provide a comprehensive history of beryl and its varieties throughout the span of history, embracing such aspects as its cultural history & lore, associated scientific knowledge and its development, the occurrences of beryl, its etymology, and the references that deal with beryl from the earliest mentions in ancient times to the present. This edition is a pared down version of “Emerald and Other Beryls.” Skip it and buy the full original edition.

synthetic gems

Gübelin reviews the diagnostic features of the latest synthetic gemstones then appearing on the market, concentrating on Lennix, Biron, Soviet and Seiko synthetic emeralds and Seiko, Lechleitner and Knischka synthetic corundums. Particular emphasis is placed on microscopic identification, especially characteristic inclusions and growth features associated with the different synthesis methods. Gübelin shows that conventional physical and optical properties may overlap substantially with those of natural stones, making internal features especially important for reliable separation. The study compares the characteristic inclusion patterns of the various products and provides practical criteria for distinguishing these increasingly sophisticated synthetics from their natural counterparts. A later English version contains 46 color figures.

corundum, Afghanistan.12, Pakistan.12, gems

gems, treatments, assembled stones, foil backing, foilback

The Gem Trade Lab Notes section (Winter 1984, p. 228) reported on emerald imitations made from colorless rock crystal quartz backed with green foil—a technique still commonly used today, even in enameled jewelry. Similarly, colorless beryl or corundum is often backed with red or green foil to mimic emerald or ruby, while silver foil may be applied behind colorless synthetic or natural sapphire to enhance its brilliance.

corundum, geology.11, gems

An edited compilation examining the geological origin, occurrence, exploration, and evaluation of gemstone deposits worldwide. The first two sections reproduce 21 contributions covering topics such as diamond formation in kimberlite, jadeite genesis through low-grade metamorphism, agate and thunder egg development, Brazilian topaz deposits, Sri Lankan sedimentary gem deposits, and the structure responsible for precious opal’s colour. Exploration studies consider magnetic characteristics associated with Australian opal deposits, sodium as a geochemical indicator of Colombian emerald mineralization, glacial tracing of Canadian kimberlite, and the economic evaluation of alluvial diamond deposits. Regional accounts describe nephrite, amethyst, agate, and other gem materials in North America. These papers are followed by VanLandingham’s extensive review of the literature and a substantial bibliography, supported by author, mineral and rock name, and subject indexes. The review encompasses gemological research, mineral composition and structure, inclusions, physical properties, and deposit geology. Particular attention is given to the conditions that produce gem-quality material and the difficulties of assessing deposits whose valuable crystals may occur irregularly within a larger mineralized body. Combining technical research with more accessible geological accounts, the volume serves as a reference for geologists, gemologists, prospectors, and collectors investigating gemstone formation and distribution.