gems, ancient gems, glyptic, archaeology, archaeogemology, ancient history, Greek, Roman, Near East, India, China, Africa, trade, commerce, trade routes

Written by the renowned authority on ancient ships and seafaring Lionel Casson, The Ancient Mariners has long served the needs of all who are interested in the sea, from the casual reader to the professional historian. This completely revised edition takes into account the fresh information that has appeared since the book was first published in 1959, especially that from archaeology's newest branch, marine archaeology. Casson does what no other author has done: he has put in a single volume the story of all that the ancients accomplished on the sea from the earliest times to the end of the Roman Empire. He explains how they perfected trading vessels from mere rowboats into huge freighters that could carry over a thousand tons, how they transformed warships from simple oared transports into complex rowing machines holding hundreds of marines and even heavy artillery, and how their maritime commerce progressed from short cautious voyages to a network that reached from Spain to India.

gems, gemology, damage assessment, diamond

The Gem Trade Laboratories of the Gemological Institute of America are frequently called on to render opinions regarding the nature of cracks and flaws in many varieties of stones. Most often, the question is whether a crack is inherent, partly inherent and extended, or due to damage that occurred after the stone was polished. It is my purpose here to set forth the methods used by the staff of the Laboratories in arriving at an opinion based on careful microscopic observations. It is common knowledge that insurance companies do not require very much information about jewelry before issuing policies and collecting premiums. Most jewelers have experienced cases where this practice has been troublesome, if not embarrassing. Few jewelers make a detailed diagram of inherent flaws in stones they sell or appraise, other than perhaps in diamonds, since insurance companies do not demand it. Therefore, stones with inherent fractures are frequently insured that may later be mistaken for damage, causing an unnecessary and time-consuming settlement. Let us reconstruct a hypothetical case in which an insured customer first believes he has damaged a stone. One day the insured trips and falls and believes that he has struck his star sapphire on the concrete floor. His first thought, after seeing that no bones are broken, is to inspect his star sapphire. For the first time the stone is examined carefully, perhaps with strong transmitted light. Sure enough, there is a crack! The insurance company and an adjuster are notified, and he sees the crack. The jeweler is notified. He inspects the stone with his loupe and admits that he sees a crack too. All too often the insurance company pays off, but not before considerable time and effort have been expended.

beryl, emerald, Rhodesia, Sandawana, Zimbabwe, gems

gems, corundum, properties.3, synthetic corundum.7, spinel, chrysoberyl, quartz, tourmaline, zircon, scapolite, spinel inclusions

inclusions, microscopy, gems

ruby, sapphire, corundum, Burma.12, jade, jadeite, fei cui, gems

Sinkankas: Both articles based on author’s many gem-buying trips and with photos taken by himself; describes geography, transport, the people, mining of gemstones, geology of deposits, mineralogy, history, recovery of jade and amber, mines, and gem trading. Obit. American Mineralogist, 59, 1974, p. 1870. Mining. [414].

corundum, ruby, sapphire, synthetic corundum.7, synthetic ruby, synthetic sapphire, gems

Chudoba and Gübelin provide a practical guide to distinguishing natural gemstones from synthetic counterparts, combining a short history of artificial gem production with detailed discussion of the principal manufacturing methods and their diagnostic consequences. The Verneuil flame-fusion process, flux growth, and hydrothermal synthesis are described, together with the characteristic structures and inclusions they produce. Particular attention is given to synthetic ruby and sapphire, spinel, emerald, and other important gem materials, with comparisons between natural and laboratory-grown stones based on growth zoning, curved striae, gas bubbles, mineral inclusions, refractive properties, fluorescence, and other microscopic and physical features. The authors emphasize examination with the gemological microscope as one of the most powerful means of separation, supported by numerous photomicrographs illustrating inclusions and growth phenomena in both natural and synthetic gems. Conceived as a concise working manual for gemologists and jewelers, the book brought together the principal identification criteria then available at a time when synthetic gemstones were becoming increasingly sophisticated and commercially important.

jade, jadeite, fei cui, California, gems

ruby, sapphire, corundum, Burma.12, gems

corundum, Australia.12, gems