gems, emerald, oiling, treatments, enhancements, fillers

This paper does not wish to deal with the luck of a Texan property owner, but rather to share my experience in the gemmological laboratory. The article could just as well be titled: What many people do not yet know about oiling emeralds, and others at times tend to forget. ”Cemmosophic” literature likes to use the French term jardin” (Engl.: garden) for typical, vei|—like inclusions visible to the naked eye. These internal structures, resembling leaves and tendrils, are commonly classified as healed fissures, but often also as open cracks. The latter are usually considered to be negative properties."

corundum, inclusions.5, treatments.6, chemistry.2, color.4, gems

gems, quartz, synthetic quartz, synthetic amethyst, Japan, hydrothermal, polysynthetic twinning

Synthetic amethysts of Japanese production, which are now available in the gem trade, are characterized with respect to their diagnostic properties such as inclusions, growth structures, twinning, and infrared spectra. The gemstones frequently have feathers consisting of liquid-filled and two-phase inclusions, sharp growth zoning parallel to one rhombohedral face, as well as twin structures. This twinning, however, can be distinguished from polysynthetic lamellar twinning in natural amethysts.

corundum, synthetic corundum.7, Lechleitner, flux, gems

Describes Lechleitner rubies consisting of natural pale ruby or colourless corundum cores from Sri Lanka covered by a thin, flux-grown synthetic ruby layer. The cores include rough, bruted and faceted material and retain natural mineral and fluid inclusions, while the synthetic overgrowth contains flux residues. Six faceted specimens show violet-tinged colours resembling Sri Lankan rubies and pink sapphires. Identification requires careful microscopic examination, particularly of the boundary between core and overgrowth, which can resemble early Knischka synthetic rubies. Trace-element analysis, including examination of flux residues, together with X-ray fluorescence, electron microprobe analysis and spectroscopy, can assist identification.

gems, beryl, emerald, inclusions, Brazil, Colombia, etc.

A comprehensive study of inclusions in emerald, with particular emphasis on their use in gemological identification and determination of geographic origin. Schwarz examines solid mineral inclusions, fluid inclusions, growth features and other internal characteristics of emeralds from the principal producing localities, comparing their characteristic inclusion assemblages. Brazilian occurrences receive extensive treatment, including Carnaíba and Socotó in Bahia, Santa Terezinha in Goiás, and deposits in Minas Gerais, alongside material from Colombia and other world sources. The work illustrates how combinations of mineral inclusions, fluid inclusions and growth structures can distinguish emeralds from different geological environments and can assist in separating natural from synthetic material. It became an important reference for subsequent studies of emerald inclusions and geographic origin. Sadly this softcover book was poorly printed on low quality paper.

natural ruby, synthetic corundum.7, gemology, twinning, inclusions.5, Sri Lanka.12, gems

corundum, sapphire, Umba, Tanzania.12, inclusions.5, gems

The many colours exhibited by corundums from Umba Valley in Tanzania are related to their varying contents of Fe, Ti, Cr and V. Ni and Co could not be detected by the EDS-XRF technique used. The presence of abundant inclusions distinguishes these gemstones, and the following were found: zircon, rutile(?), apatite, hematite, mica, monazite, plagioclase, calcite, pyrrhotine and graphite. Healed fractures, negative crystals, colour zoning, twinning with traces of intersecting lamellae and boehmite(?) laths were noted. Techniques for the identification of inclusions are discussed. The densities (3.98–4.01 g/cm³) and refractive indices (nₑ 1.761–1.768, nₒ 1.769–1.778) were also determined. Spectral features are given.

quartz, inclusions, gems

Gübelin and Koivula present a photographic survey of inclusions in quartz, illustrating the remarkable variety of solid, liquid and gaseous features that may occur within the mineral. The examples demonstrate mineral crystals, fluid inclusions, growth phenomena and other internal structures, emphasizing both their visual diversity and their value for interpreting the formation of their quartz hosts. The article consists principally of selected photomicrographs from the authors’ Photoatlas of Inclusions in Gemstones, accompanied by explanatory captions. A contemporary Journal of Gemmology abstract specifically describes it as a series of color photographs taken from the Photoatlas and records 42 color figures.

gems, corundum, treatments.6, inclusions.5, Sri Lanka.12

The question of how to identify natural-colored from heat-treated corundum has long puzzled the gemological community. One important clue is now provided b y carbon dioxide fluid inclusions. Because such inclusions cannot survive heat treatment, their existence intact and unruptured in rubies and sapphires i s conclusive proof that n o heat treatment has occurred.

natural ruby, synthetic corundum.7, gemology, inclusions.5, gems

Schmetzer presents a comprehensive study of the identification and separation of natural and synthetic rubies, based on examination of approximately 900 natural and 350 synthetic stones. After reviewing the mineralogy and crystallography of corundum, he describes five principal methods of synthetic ruby growth and the analytical techniques employed, including microscopy, UV-visible and infrared spectroscopy, ultraviolet fluorescence, goniometry and chemical analysis. The principal emphasis is on microscopic inclusions and internal growth structures: rutile, boehmite, twinning and characteristic growth features are discussed as evidence of natural origin, while diagnostic inclusions and structures in synthetic material are related to particular growth processes and manufacturers. Natural rubies from 15 localities are described and compared, followed by similarly organized accounts of 11 types of synthetic ruby. The work is extensively illustrated and intended as a practical reference for determining whether a ruby is natural or synthetic and, in many cases, establishing its geographic source or method of synthesis.