Friday, August 03, 2007
That's Quite A Rock
Ying Wu writes about rough diamond jewelry on the rise + the quickening fashion cycles + other viewpoints @ http://online.wsj.com/article/SB118557885150080861.html?mod=home_we_banner_left&mod=livemint
Hydrostatic Weighing Method
Advantages
- The major advantage is that an exact specific gravity (SG) figure can be arrived at.
- There is no limitation on the specific gravity (SG) of the stones that can be calculated. Unlike heavy liquids, high SG stones can be tested just as accurately as low SG stones.
Disadvantages
The accuracy of this method depends on several things:
- The accuracy of the balance. The balance should be able to weigh stones to 0.01 carat. If not, degree of error will be too large.
- The size of the stone is of great importance. With a ruby weighing 2 carats, an error of just 0.01 carat in the water weighing will lead to an error of 0.08 in the final SG determination, which is qute serious. It is generally agreed that even with a very accurate balance, this method should not be used with stones of less than one carat.
- The expertise and skill of the person making the measurements is also important. There are possibilities for error in both the weighing and the calculations. Things such as surface tension and air bubbles in the water can also affect the results.
- The hydrostatic method is rather time consuming and even someone with a great deal of experience usually needs several minutes to calculate the SG of a single stone.
- The major advantage is that an exact specific gravity (SG) figure can be arrived at.
- There is no limitation on the specific gravity (SG) of the stones that can be calculated. Unlike heavy liquids, high SG stones can be tested just as accurately as low SG stones.
Disadvantages
The accuracy of this method depends on several things:
- The accuracy of the balance. The balance should be able to weigh stones to 0.01 carat. If not, degree of error will be too large.
- The size of the stone is of great importance. With a ruby weighing 2 carats, an error of just 0.01 carat in the water weighing will lead to an error of 0.08 in the final SG determination, which is qute serious. It is generally agreed that even with a very accurate balance, this method should not be used with stones of less than one carat.
- The expertise and skill of the person making the measurements is also important. There are possibilities for error in both the weighing and the calculations. Things such as surface tension and air bubbles in the water can also affect the results.
- The hydrostatic method is rather time consuming and even someone with a great deal of experience usually needs several minutes to calculate the SG of a single stone.
Rutile
Chemistry: Titanium dioxide (polymorphous with anatase and brookite)
Crystal system: Tetragonal; vertically striated prisms capped with pyramids; geniculate twins; sometimes repeated twinning causes closed rings.
Color: Rarely transparent; red, brown, black; too dark for gem.
Hardness: 6 – 6.5
Cleavage: Distinct: 1 direction; fracture: brittle, conchoidal to uneven.
Specific gravity: 4.2 – 4.3
Refractive index: 2.62 – 2.90; Uniaxial positive; 0.287
Luster: Adamantine to metallic.
Dispersion: Very high.
Dichroism: Strong but variable.
Occurrence: Found in igneous rocks, pegmatites, metamorphic rocks and limestones.
Notes
Common as inclusion in quartz (rutilated quartz) and a wide variety of gems; made synthetically as diamond simulant with yellow tint, high DR and strong dispersion; faceted for collectors.
Crystal system: Tetragonal; vertically striated prisms capped with pyramids; geniculate twins; sometimes repeated twinning causes closed rings.
Color: Rarely transparent; red, brown, black; too dark for gem.
Hardness: 6 – 6.5
Cleavage: Distinct: 1 direction; fracture: brittle, conchoidal to uneven.
Specific gravity: 4.2 – 4.3
Refractive index: 2.62 – 2.90; Uniaxial positive; 0.287
Luster: Adamantine to metallic.
Dispersion: Very high.
Dichroism: Strong but variable.
Occurrence: Found in igneous rocks, pegmatites, metamorphic rocks and limestones.
Notes
Common as inclusion in quartz (rutilated quartz) and a wide variety of gems; made synthetically as diamond simulant with yellow tint, high DR and strong dispersion; faceted for collectors.
Thursday, August 02, 2007
Napoleon Bonaparte
Clearly, the pleasures wines afford are transitory – but so are those of the ballet, or of a musical performance. Wine is inspiring and adds greatly to the joy of living.
Colorless Coatings And Impregnations
A number of essentially colorless substances have been used to coat the surface of gemstones; the primary purpose being to improve the apparent polish by masking small scratches, a grainy texture, or other surface irregularities. Coatings are also used to protect underlying dye treatments. Such treatments are primarily used on aggregate gem materials and those consisting of more than one material.
Aggregates like jadeite and nephrite have a tendency to have small crystals pulled from their surfaces during polishing. Other gem materials like lapis lazuli may show similar characteristics because they contain minerals of different hardness, resulting in the stone not polishing to an even surface. Other gem materials that may be coated include amazonite feldspar, alabaster, marble, rhodochrosite, serpentine, soapstone, and turquoise.
Among the most commonly used colorless coating materials are waxes and paraffin. Under magnification the application of a needle probe may reveal wax by removing some of it, while the application of a heated needle may cause the coating to liquefy and flow. Drill holes on beads are a good area to check as such surface coatings tend to concentrate in these.
Plastics are a class of somewhat more durable substances used to surface-coat gem materials. These too may be detected under magnification by the ability to scratch them with a needle probe. A needle may also be used to remove a small amount of a plastic coating, which then might be heated to reveal a characteristic acrid odor. A relatively thick plastic coating might be detected on the refractometer, where a reading for the plastic, or both the plastic and underlying gem material, could be seen.
Colorless impregnations are used on gem materials for a number of reasons. They are used to stabilize porous stones like turquoise by preventing skin oils from producing undesirable color changes. Some materials, because of their porous surface have a whitish chalky appearance due to the scattering effects these surface have on incident light; this can be minimized by a colorless impregnation. Such treatment is used on low quality turquoise, producing an improvement in color; it is also used on some porous, chalky opal from Brazil that does not reveal its play of color without such treatment.
Aggregates like jadeite and nephrite have a tendency to have small crystals pulled from their surfaces during polishing. Other gem materials like lapis lazuli may show similar characteristics because they contain minerals of different hardness, resulting in the stone not polishing to an even surface. Other gem materials that may be coated include amazonite feldspar, alabaster, marble, rhodochrosite, serpentine, soapstone, and turquoise.
Among the most commonly used colorless coating materials are waxes and paraffin. Under magnification the application of a needle probe may reveal wax by removing some of it, while the application of a heated needle may cause the coating to liquefy and flow. Drill holes on beads are a good area to check as such surface coatings tend to concentrate in these.
Plastics are a class of somewhat more durable substances used to surface-coat gem materials. These too may be detected under magnification by the ability to scratch them with a needle probe. A needle may also be used to remove a small amount of a plastic coating, which then might be heated to reveal a characteristic acrid odor. A relatively thick plastic coating might be detected on the refractometer, where a reading for the plastic, or both the plastic and underlying gem material, could be seen.
Colorless impregnations are used on gem materials for a number of reasons. They are used to stabilize porous stones like turquoise by preventing skin oils from producing undesirable color changes. Some materials, because of their porous surface have a whitish chalky appearance due to the scattering effects these surface have on incident light; this can be minimized by a colorless impregnation. Such treatment is used on low quality turquoise, producing an improvement in color; it is also used on some porous, chalky opal from Brazil that does not reveal its play of color without such treatment.
In Spite Of The Gods
Good Books: (via Emergic) Here is a brief about the book from Random House:
India remains a mystery to many Americans, even as it is poised to become the world’s third largest economy within a generation, outstripping Japan. It will surpass China in population by 2032 and will have more English speakers than the United States by 2050. In In Spite of the Gods, Edward Luce, a journalist who covered India for many years, makes brilliant sense of India and its rise to global power. Already a number-one bestseller in India, his book is sure to be acknowledged for years as the definitive introduction to modern India.
In Spite of the Gods illuminates a land of many contradictions. The booming tech sector we read so much about in the West, Luce points out, employs no more than one million of India’s 1.1 billion people. Only 35 million people, in fact, have formal enough jobs to pay taxes, while three-quarters of the country lives in extreme deprivation in India’s 600,000 villages. Yet amid all these extremes exists the world’s largest experiment in representative democracy and a largely successful one, despite bureaucracies riddled with horrifying corruption.
Luce shows that India is an economic rival to the U.S. in an entirely different sense than China is. There is nothing in India like the manufacturing capacity of China, despite the huge potential labor force. An inept system of public education leaves most Indians illiterate and unskilled. Yet at the other extreme, the middle class produces ten times as many engineering students a year as the United States. Notwithstanding its future as a major competitor in a globalized economy, American leaders have been encouraging India’s rise, even welcoming it into the nuclear energy club, hoping to balance China’s influence in Asia.
The Guardian reviewed Edward Luce’s book in August:
Several recent books have examined the savage inequalities between the country's burgeoning, educated, urban elite and the shockingly poor who live in the vast hinterlands. Luce's thoughtful and thorough book - 'an unsentimental evaluation of contemporary India against the backdrop of its widely expected ascent to great power status in the 21st century' - fits right into this category. He suggests the dichotomy of India in the book's subtitle and later calls India's rise 'strange' because, while becoming an important political and economic force, it has remained 'an intensely religious, spiritual and, in some ways, superstitious society'.
It is always difficult to structure a book like this one, but Luce manages well by breaking up the narrative into neat chapters, each dealing with a different theme and each capable of standing on its own feet. We are offered accounts of India's 'schizophrenic' flourishing economy; its state machinery; its caste conflicts; the rise of Hindu nationalism; the dynastic nature of its politics; its relationship with Pakistan and its Muslim minority; its relationship with the US and China; the country's experience of grappling with modernity and urbanization.
The Hindu Business Line had a detailed review of Luce’s book:
The book concludes with a discussion of India's huge opportunities and challenges in the twenty-first century. Judging by the living conditions of ordinary Indians, rather than by the drama of national events, Luce is of the view that the country is moving forward on a remarkably stable trajectory. And, as opposed to China, India has given a higher priority to stability than it has to efficiency.
'India is like a lorry with twelve wheels. If one or two puncture, it doesn't go into the ditch,' is a quote of Myron Weiner that he cites. That way, China may have fewer wheels so it can travel faster, but 'people far beyond China's borders worry about what would happen if a wheel came off,' notes Luce, extending Weiner's analogy.
Though investors are deterred by the babus, institutional advantages such as an independent judiciary and a free media' may make India the proverbial tortoise that can overtake the Chinese hare, postulates the author. India can also draw on a deep well of intellectual capital.
Yet, for those closer home, a word of caution is not to take our economic strengths for granted. As the joke goes, 'India never misses an opportunity to miss an opportunity'. It is also suffering from a premature spirit of triumphalism, alerts Luce.
I think Luce's book is about the new but morphing India. It's an insightful book about India, and Luce brings an outsider's perspective.
India remains a mystery to many Americans, even as it is poised to become the world’s third largest economy within a generation, outstripping Japan. It will surpass China in population by 2032 and will have more English speakers than the United States by 2050. In In Spite of the Gods, Edward Luce, a journalist who covered India for many years, makes brilliant sense of India and its rise to global power. Already a number-one bestseller in India, his book is sure to be acknowledged for years as the definitive introduction to modern India.
In Spite of the Gods illuminates a land of many contradictions. The booming tech sector we read so much about in the West, Luce points out, employs no more than one million of India’s 1.1 billion people. Only 35 million people, in fact, have formal enough jobs to pay taxes, while three-quarters of the country lives in extreme deprivation in India’s 600,000 villages. Yet amid all these extremes exists the world’s largest experiment in representative democracy and a largely successful one, despite bureaucracies riddled with horrifying corruption.
Luce shows that India is an economic rival to the U.S. in an entirely different sense than China is. There is nothing in India like the manufacturing capacity of China, despite the huge potential labor force. An inept system of public education leaves most Indians illiterate and unskilled. Yet at the other extreme, the middle class produces ten times as many engineering students a year as the United States. Notwithstanding its future as a major competitor in a globalized economy, American leaders have been encouraging India’s rise, even welcoming it into the nuclear energy club, hoping to balance China’s influence in Asia.
The Guardian reviewed Edward Luce’s book in August:
Several recent books have examined the savage inequalities between the country's burgeoning, educated, urban elite and the shockingly poor who live in the vast hinterlands. Luce's thoughtful and thorough book - 'an unsentimental evaluation of contemporary India against the backdrop of its widely expected ascent to great power status in the 21st century' - fits right into this category. He suggests the dichotomy of India in the book's subtitle and later calls India's rise 'strange' because, while becoming an important political and economic force, it has remained 'an intensely religious, spiritual and, in some ways, superstitious society'.
It is always difficult to structure a book like this one, but Luce manages well by breaking up the narrative into neat chapters, each dealing with a different theme and each capable of standing on its own feet. We are offered accounts of India's 'schizophrenic' flourishing economy; its state machinery; its caste conflicts; the rise of Hindu nationalism; the dynastic nature of its politics; its relationship with Pakistan and its Muslim minority; its relationship with the US and China; the country's experience of grappling with modernity and urbanization.
The Hindu Business Line had a detailed review of Luce’s book:
The book concludes with a discussion of India's huge opportunities and challenges in the twenty-first century. Judging by the living conditions of ordinary Indians, rather than by the drama of national events, Luce is of the view that the country is moving forward on a remarkably stable trajectory. And, as opposed to China, India has given a higher priority to stability than it has to efficiency.
'India is like a lorry with twelve wheels. If one or two puncture, it doesn't go into the ditch,' is a quote of Myron Weiner that he cites. That way, China may have fewer wheels so it can travel faster, but 'people far beyond China's borders worry about what would happen if a wheel came off,' notes Luce, extending Weiner's analogy.
Though investors are deterred by the babus, institutional advantages such as an independent judiciary and a free media' may make India the proverbial tortoise that can overtake the Chinese hare, postulates the author. India can also draw on a deep well of intellectual capital.
Yet, for those closer home, a word of caution is not to take our economic strengths for granted. As the joke goes, 'India never misses an opportunity to miss an opportunity'. It is also suffering from a premature spirit of triumphalism, alerts Luce.
I think Luce's book is about the new but morphing India. It's an insightful book about India, and Luce brings an outsider's perspective.
Top Ten Trends In Contemporary Art
Robin Cembalest writes about trends among trends + the themes behind their work + complexity and richness of their performances @ http://artnews.com/issues/article.asp?art_id=2002
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