Dr Luigi Constantini, geologist and gemologist with the International Gemological Institute Italy, has written The Slovak Opal: A Rediscovery of the Queen of Gems for Gem Lovers and Tourists.
The book describes the historical as well as mineralogical and gemological aspect of Slovak opal. The book also explains the classification of Slovak opal, quality grading with glossary and index for quick reference.
The book is available @ www.e-igi.com/estore
Sunday, February 11, 2007
The Federal Trade Commission’s Guide for the Jewelry, Precious Metals and Pewter Industries
FTC writes:
23.16 Misuse of the words "brilliant" and "full cut."
It is unfair or deceptive to use the unqualified expressions "brilliant," "brilliant cut," or "full cut" to describe, identify, or refer to any diamond except a round diamond that has at least thirty-two (32) facets plus the table above the girdle and at least twenty-four (24) facets below.
Note to 23.16: Such terms should not be applied to single or rose-cut diamonds. They may be applied to emerald-(rectangular) cut, pear-shaped, heart-shaped, oval-shaped, and marquise-(pointed oval) cut diamonds meeting the above-stated facet requirements when, in immediate conjunction with the term used, the form of the diamond is disclosed.
More info @ http://www.ftc.gov/bcp/guides/jewel-gd.htm
23.16 Misuse of the words "brilliant" and "full cut."
It is unfair or deceptive to use the unqualified expressions "brilliant," "brilliant cut," or "full cut" to describe, identify, or refer to any diamond except a round diamond that has at least thirty-two (32) facets plus the table above the girdle and at least twenty-four (24) facets below.
Note to 23.16: Such terms should not be applied to single or rose-cut diamonds. They may be applied to emerald-(rectangular) cut, pear-shaped, heart-shaped, oval-shaped, and marquise-(pointed oval) cut diamonds meeting the above-stated facet requirements when, in immediate conjunction with the term used, the form of the diamond is disclosed.
More info @ http://www.ftc.gov/bcp/guides/jewel-gd.htm
Gemstones And Their Origins
By Peter C Keller
Van Nostrand Reinhold
1990 ISBN 0-442-31945-2
Van Nostrand Reinhold writes:
The closest most people ever come to experiencing gemstones at their source is at the jeweler’s case. This book takes you to many of their classic sources: the rich alluvial deposits of Sri Lanka, where precious stones lie exposed on gravel riverbeds; to Chantaburi-Trat, Thailand, where rubies are brought to the earth’s surface embedded in volcanic magma; to the black emerald-bearing veins of Muzo, Colombia; to the source of Australia’s Argyle diamond deposit—the most productive in the world, yet undiscovered until 1980.
Gemstones and Their Origins is the first major work devoted to the origins of precious stones: how they form, where they are found, and how they are recovered. Rigorous in scientific detail and lavish in illustrations, it explores the major geological processes responsible for the formation of gem deposits and then examines, on location, nine classic gem deposits from around the globe.
Peter C Keller takes you on a geologist’s tour of the world’s most famous and geologically significant gem deposits. Keller traces the origin of gems at each of four principle gem forming sources. First, we view the development of gemstones deposited by water on the earth’s surface. Here we encounter the gem gravels of Sri Lanka, opal deposits of Australia, and ruby and zircon from Indochina.
Next, we explore gemstones formed by molten rock—the hydrothermal emerald deposits of Colombia, the pegmatites of Minas Gerais, Brazil, and the rubies of Chantaburi-Trat in Thailand, brought to the earth’s surface in volcanic flows. As we go deeper into the earth’s crust, we encounter the world famous ruby deposits of Mogok, Burma, and jade deposits of northern Burma, one of few known examples of high pressure regional metamorphism.
Our descent into the earth’s crust ends some 100 miles below the earth’s surface. Here, in conditions of super high pressure and temperature, peridot and diamond form. Examples from the classic peridot of Zabargad and the recently discovered diamonds at Argyle in Western Australia are examined.
Along the way, Peter Keller documents this geological field trip with the outstanding photographs of Harold and Erica Van Pelt, renowned as the leading photographers of gems and mineral specimens in the world today. More than 100 stunning color photographs depict rough and cut stones and the often primitive places where they are mined. Useful maps, some in color, and an exhaustive bibliography make this the definitive reference work on the subject for gemologists and geologists, collectors and dealers, students and gem lovers.
Van Nostrand Reinhold
1990 ISBN 0-442-31945-2
Van Nostrand Reinhold writes:
The closest most people ever come to experiencing gemstones at their source is at the jeweler’s case. This book takes you to many of their classic sources: the rich alluvial deposits of Sri Lanka, where precious stones lie exposed on gravel riverbeds; to Chantaburi-Trat, Thailand, where rubies are brought to the earth’s surface embedded in volcanic magma; to the black emerald-bearing veins of Muzo, Colombia; to the source of Australia’s Argyle diamond deposit—the most productive in the world, yet undiscovered until 1980.
Gemstones and Their Origins is the first major work devoted to the origins of precious stones: how they form, where they are found, and how they are recovered. Rigorous in scientific detail and lavish in illustrations, it explores the major geological processes responsible for the formation of gem deposits and then examines, on location, nine classic gem deposits from around the globe.
Peter C Keller takes you on a geologist’s tour of the world’s most famous and geologically significant gem deposits. Keller traces the origin of gems at each of four principle gem forming sources. First, we view the development of gemstones deposited by water on the earth’s surface. Here we encounter the gem gravels of Sri Lanka, opal deposits of Australia, and ruby and zircon from Indochina.
Next, we explore gemstones formed by molten rock—the hydrothermal emerald deposits of Colombia, the pegmatites of Minas Gerais, Brazil, and the rubies of Chantaburi-Trat in Thailand, brought to the earth’s surface in volcanic flows. As we go deeper into the earth’s crust, we encounter the world famous ruby deposits of Mogok, Burma, and jade deposits of northern Burma, one of few known examples of high pressure regional metamorphism.
Our descent into the earth’s crust ends some 100 miles below the earth’s surface. Here, in conditions of super high pressure and temperature, peridot and diamond form. Examples from the classic peridot of Zabargad and the recently discovered diamonds at Argyle in Western Australia are examined.
Along the way, Peter Keller documents this geological field trip with the outstanding photographs of Harold and Erica Van Pelt, renowned as the leading photographers of gems and mineral specimens in the world today. More than 100 stunning color photographs depict rough and cut stones and the often primitive places where they are mined. Useful maps, some in color, and an exhaustive bibliography make this the definitive reference work on the subject for gemologists and geologists, collectors and dealers, students and gem lovers.
Saturday, February 10, 2007
Consumption Level Goes North As India Shines
(via Times News Network) Rajesh Shukla & Preeti Kakar writes:
The Indian economy has ushered in a new era, wherein the country’s per capita income growth in recent years has outperformed that of the other major Asian economies. However, the gains of prosperity have been distributed unevenly. The paradox of plenty amid poverty ceases to lift. For instance, per capita income in the richest state of the country is about five times that of the poorest.
India’s economic diversity matches its social diversity and this engenders a wide spectrum of consumers in terms of their income levels and spending behaviour. What is noteworthy here is that the diversity is not only visible in the spending behaviour of people with different levels of income but also with the same level of income. This is because income levels by themselves do not reveal much about market behaviour and purchasing power.
More info @ http://economictimes.indiatimes.com/articleshow/1581481.cms
The Indian economy has ushered in a new era, wherein the country’s per capita income growth in recent years has outperformed that of the other major Asian economies. However, the gains of prosperity have been distributed unevenly. The paradox of plenty amid poverty ceases to lift. For instance, per capita income in the richest state of the country is about five times that of the poorest.
India’s economic diversity matches its social diversity and this engenders a wide spectrum of consumers in terms of their income levels and spending behaviour. What is noteworthy here is that the diversity is not only visible in the spending behaviour of people with different levels of income but also with the same level of income. This is because income levels by themselves do not reveal much about market behaviour and purchasing power.
More info @ http://economictimes.indiatimes.com/articleshow/1581481.cms
Friday, February 09, 2007
Garnet And Glass Doublet
A garnet and glass doublet, also known as garnet-topped doublet (GTD) consists of a thin cap of almandine garnet fused to a piece of colored glass imitating a gem. The doublet was popular in the 18th and 19th century, and may still turn up in antique jewelry today.
The reason for constructing this type of doublet is to increase the surface luster on the table of a gemstone. For those who are unaware may think the stone is valuable, but it is easily detectable by the following means.
- The first step is to clean and examine the stone. Visual observation provides you with the chance to examine and classify all aspects of the physical appearance of the gem.
- Check the refractive index. Refractive index of the table will be that of almandine (1.76 or above).
- Refractive index of any pavilion facet will be within the glass range (1.50 - 1.70).
- Use the microscope. The luster difference between garnet top and the glass will become obvious.
- Do the red-ring test by placing the garnet-topped doublet face down on a white background. You will see a faint red ring inside the girdle outline representing the boundary of the garnet cap.
- Immersion technique. When you immerse the stone in a suitable liquid, you are able to see any color difference between the two materials.
- Fluorescence. This is a complimentary test. View the gem parallel to the girdle plane under long wave and short wave ultraviolet light. Garnet will show inert reaction, while glass may show chalky fluorescence.
The reason for constructing this type of doublet is to increase the surface luster on the table of a gemstone. For those who are unaware may think the stone is valuable, but it is easily detectable by the following means.
- The first step is to clean and examine the stone. Visual observation provides you with the chance to examine and classify all aspects of the physical appearance of the gem.
- Check the refractive index. Refractive index of the table will be that of almandine (1.76 or above).
- Refractive index of any pavilion facet will be within the glass range (1.50 - 1.70).
- Use the microscope. The luster difference between garnet top and the glass will become obvious.
- Do the red-ring test by placing the garnet-topped doublet face down on a white background. You will see a faint red ring inside the girdle outline representing the boundary of the garnet cap.
- Immersion technique. When you immerse the stone in a suitable liquid, you are able to see any color difference between the two materials.
- Fluorescence. This is a complimentary test. View the gem parallel to the girdle plane under long wave and short wave ultraviolet light. Garnet will show inert reaction, while glass may show chalky fluorescence.
Gems And Gem Art
Programa Royal Collections Group writes:
Gazing at the world’s biggest topaz, enjoying the rare sight of a gem embedded in a meteorite or marvelling at centuries-old sculptures made from precious stones are all culturally enriching experiences for people from all walks of life.
But the aim of PRC (Programa Royal Collection) is not only to exhibit unique collections but also to convert these experiences into a discovering and learning process that goes well beyond mere passive observation. This twofold experience of enjoying and learning in tandem is the keynote idea of our exhibition philosophy.
In the case of the gem exhibitions, for example, the precious stones are accompanied with educational display cases containing such exhibits as gemmological maps, uncut gems, laboratory material, polishing and cutting equipment, etc., all designed to raise public awareness of gems and gem art. These display cases are backed up by a wealth of informative material in different languages and with different levels of specialisation: posters for display cases, information panels, photographs, fact files, brochures, catalogues, etc. Visitors are thus enabled to discover numerous aspects of the world of gems, such as their formation, mining, physical characteristics (hardness, optical effects, cleavage...), cutting, authentication, what makes a synthetic gem different from a false gem and many other fascinating facts and snippets.
More info @ http://www.royalcollections.es/ingles/queofreceprc/interesdidactico/interesdidactico.htm
Gazing at the world’s biggest topaz, enjoying the rare sight of a gem embedded in a meteorite or marvelling at centuries-old sculptures made from precious stones are all culturally enriching experiences for people from all walks of life.
But the aim of PRC (Programa Royal Collection) is not only to exhibit unique collections but also to convert these experiences into a discovering and learning process that goes well beyond mere passive observation. This twofold experience of enjoying and learning in tandem is the keynote idea of our exhibition philosophy.
In the case of the gem exhibitions, for example, the precious stones are accompanied with educational display cases containing such exhibits as gemmological maps, uncut gems, laboratory material, polishing and cutting equipment, etc., all designed to raise public awareness of gems and gem art. These display cases are backed up by a wealth of informative material in different languages and with different levels of specialisation: posters for display cases, information panels, photographs, fact files, brochures, catalogues, etc. Visitors are thus enabled to discover numerous aspects of the world of gems, such as their formation, mining, physical characteristics (hardness, optical effects, cleavage...), cutting, authentication, what makes a synthetic gem different from a false gem and many other fascinating facts and snippets.
More info @ http://www.royalcollections.es/ingles/queofreceprc/interesdidactico/interesdidactico.htm
All About Eve
A memorable quote from the movie:
Margo Channing (Bette Davis): Funny business, a woman's career, the things you drop on the way up the ladder so you can move faster. You forget you'll need them again when you get back to being a woman. It's one career all females have in common - being a woman. Sooner or later we've got to work at it no matter how many other careers we've had or wanted. And in the last analysis nothing is any good unless you can look up just before dinner or turn around in bed and there he is. Without that you're not a woman. You're something with a French provincial office or a book full of clippings but you're not a woman. Slow curtain, the end.
Margo Channing (Bette Davis): Funny business, a woman's career, the things you drop on the way up the ladder so you can move faster. You forget you'll need them again when you get back to being a woman. It's one career all females have in common - being a woman. Sooner or later we've got to work at it no matter how many other careers we've had or wanted. And in the last analysis nothing is any good unless you can look up just before dinner or turn around in bed and there he is. Without that you're not a woman. You're something with a French provincial office or a book full of clippings but you're not a woman. Slow curtain, the end.
The Federal Trade Commission’s Guide for the Jewelry, Precious Metals and Pewter Industries
FTC writes:
23.15 Misuse of the term "properly cut," etc.
It is unfair or deceptive to use the terms "properly cut," "proper cut," "modern cut," or any representation of similar meaning to describe any diamond that is lopsided, or is so thick or so thin in depth as to detract materially from the brilliance of the stone.
Note to 23.15: Stones that are commonly called "fisheye" or "old mine" should not be described as "properly cut," "modern cut," etc.
More info @ http://www.ftc.gov/bcp/guides/jewel-gd.htm
23.15 Misuse of the term "properly cut," etc.
It is unfair or deceptive to use the terms "properly cut," "proper cut," "modern cut," or any representation of similar meaning to describe any diamond that is lopsided, or is so thick or so thin in depth as to detract materially from the brilliance of the stone.
Note to 23.15: Stones that are commonly called "fisheye" or "old mine" should not be described as "properly cut," "modern cut," etc.
More info @ http://www.ftc.gov/bcp/guides/jewel-gd.htm
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