corundum, color.4, synthetic corundum.7, gems

In the lab and marketplace alike, gemologists and gem traders seek to separate natural ruby from synthetic with training and gemological equipment. But what if there was an easier, faster method? Presidium, in collaboration with the Gem and Jewelry Institute of Thailand (GIT), recently released a Synthetic Ruby Identifier (SRI) designed to separate natural ruby from synthetic flame fusion ruby. Bangkok’s Lotus Gemology laboratory was given the opportunity to try out this new instrument to evaluate its utility and accuracy.

corundum, Burma.12, Geology.11, Mogok, ruby, sapphire, gems

The Mogok Stone Tract is situated in Myanmar’s Mandalay province, some 200 km northeast of Mandalay. Home to the world’s premier ruby mines, it is also one of the richest mineral concentrations on Earth. Aside from ruby, Mogok produces a potpourri of gems, including sapphire, spinel, peridot, topaz and moonstone, to name but a few. One of Mogok’s gems, painite, is found nowhere else on the planet. With over fifty different gem species mined at Mogok, in terms of gemological diversity, perhaps only Sri Lanka can compare.

corundum, inclusions.5, quality.10, Burma.12, Kashmir.12, India.12, gems

Prior to the 1930s, ruby and sapphire were mysteries, arcane gems oft-confused with spinel and other look-alikes. Enter Col. J.F. Halford-Watkins. Living in Mogok for more than two decades, he penned several articles and an entire monograph on the subject of these rare gems. Sadly he passed away before it could be published. In 1994, Richard Hughes came across a reference to the manuscript. Patrick Streeter, grandson of G. Skelton Streeter, and great grandson of the famed London jeweler, Edwin Streeter, had mentioned the Halford-Watkins manuscript while writing his book, Streeter of Bond Street. Following up on that obscure reference Richard Hughes stumbled upon something truly fantastic, an undiscovered treasure of the gemological literature. Over ten years in the making, The Book of Ruby and Sapphire is the realization of Halford-Watkins’ vision. Professionally edited and illustrated, it represents a gemological tour de force.

jade, nephrite, China, Xinjiang, Khotan, Hotan, gems

An investigation into nephrite and imitation nephrite pebbles purchased in Guangzhou, China's Hualin Street jade market.

spinel, Burma, Tanzania, Vietnam, Sri Lanka, Madagascar, corundum, Quality.10, gems

A lavishly illustrated celebration of spinel, combining spectacular gem photography with accounts of the stone’s principal sources and the people and landscapes associated with them. Yavorskyy and Hughes trace spinel from the historic deposits of Myanmar (Burma), Tajikistan and Sri Lanka to important newer discoveries in Vietnam, Tanzania and Madagascar, presenting exceptional specimens and faceted gems alongside scenes from mining areas and the gem trade. Rather than serving as a conventional scientific gemology text, the book emphasizes the beauty, diversity and geographic origins of spinel, documenting its remarkable range of colors and highlighting a gemstone long overshadowed by ruby and sapphire.

spinel, Burma, Tanzania, Vietnam, Sri Lanka, Madagascar, gems

Spinel is rising. Like a phoenix, a gem that for centuries was associated with power, fire, beauty and life, is back again. Over the past several years, interest in spinel has grown and I am delighted to see the newfound fame for classic gem. I first became interested in gemology while studying the history of the 100 Years’ War between France and England. Who could forget the Black Prince’s Ruby, a stone given by the Spanish king to the Black Prince of England as payment for his military support in the civil war of 1366. Later, in 1415, the stone was said to have saved the life of King Henry V of England at the battle of Agincourt. Henry, who had placed the large red orb on his helmet, was struck by the battle axe of the French Duke of Alencon. Sword hit stone; both the ruby and Henry survived. If these stories were not already amazing enough, imagine a costly military campaign paid for entirely with a single gemstone. These are the legends of the Black Prince’s Ruby. But my greatest astonishment was learning that that the gem was not a ruby at all but, in fact, a red spinel. Since I had no idea what a spinel was, I decided to learn more about this mysterious gem. Thus began my interest in gemology. The gemology of spinel is a pleasure. Unlike ruby, there are few treatments and separation from both synthetics and simulants is straightforward. Nevertheless spinel is a rich subject, with a history nearly as long as ruby itself. The past fame, disgrace and recent resurrection of the gem are a lesson in the importance of nomenclature in marketing. Since gemology is truly a human science—mixing science, history, geography, art, trade and terminology—we must understand that human emotion is a crucial factor in marketing. Gems, even if rare and beautiful, also need a good name, and spinel is a classic example of that fact.

corundum, geology.11, Madagascar.12, gems

It is evening in the Madagascan town of Andilamena. In a small restaurant, three Hogmies and one Malagasy pore over a map, intensely focused on a blank spot where no road goes, miles from the nearest settlement. The Hogmies have traveled halfway around the world to visit this miniscule cartographic smudge of tightly wound contour lines. For it is here that Madagascar’s finest sapphires are said to be found. But perhaps I am getting ahead of myself. Let me begin a bit further back... My first recollection of Madagascar was grade school, where we dutifully learned that a prehistoric fish, long thought extinct, had been fished from the coastal waters of this errant isle. Later, in gemology class, my teacher again brought up the subject of this forgotten land, mentioning that the famous French naturalist, Alfred Lacroix had written a paper about it (Un Voyage au Pays des Béryls). From that moment on, Madagascar became known to me not just as something out of a Jules Verne novel, but as the “Beryl Island.” The Island of Madagascar is an anomaly in many respects. While lying just 400 km from the coast of Africa, it was not settled until roughly 2000 years ago, and not by Africans, but by adventurous sailors from the Malayo-Indonesian Archipelago, some 6400 km to the east. Today the country’s human population is a tumultuous stew spiced with Malay, African, Arab, French, Chinese and Indian ingredients.

corundum, inclusions.5, photomicrography, gems

A gemologist’s life would be far easier if gems were cut as parallel-sided plates. But they’re not. Facets are designed to reflect light back to the viewer, not transmit it. This means light entering the gemstone from behind (transmitted light) will typically not pass straight through. If we want to see inclusions, we must constantly change the light paths through the gemstone. This is done by changing the position of the gemstone relative to the light and changing the light relative to the gem. The most versatile and controllable method of doing this is with the fiber-optic light, an illumination technique “darker” than even darkfield. During a recent routine identification of a natural chrysoberyl a startling difference in two distinctly different types of illumination commonly used in the examination of gemstones was clearly revealed. These two methods are darkfield and fiber-optic illumination. When this chrysoberyl was studied in darkfield (Figure 1), only a fine linear growth band was seen. However, when fiber-optic lighting was directed in along the girdle plane, bundles of fine light-scattering silky needles extending at 90˚ from the linear growth band became abundantly clear. At the same time the linear growth band itself was also more clearly detailed (Figure 2). The difference in the amount of visual information provided by these two different lighting techniques was startling. In this instance darkfield was clearly inferior to fiber-optic illumination.

corundum, synthetic corundum.7, gems

Virtually all gemologists are aware of the curved growth lines and gas bubbles in Verneuil (flame-fusion) synthetic corundum, but few understand exactly why they occur and how they are distributed in these stones. This article clarifies these important identifying features.

corundum, color.4, treatments.6, gems

One of the greatest gemological challenges is determining if a ruby or sapphire has been heat treated. UV fluorescence can assist in that identification, as well as detecting fillers in emerald.