Tuesday, October 02, 2007
The 10 Most Expensive Living Artists
Kelly Devine Thomas profiles the most expensive living artists @ http://artnews.com/issues/article.asp?art_id=1520
Selling Diamonds
(via Diamond Promotion Service) Diamond Mining: 15. It is believed that diamonds were formed by heat and pressure, millions of years ago, deep within the earth. Later, the magma in which the diamonds were embedded was forced to the surface through fissures like the throats of ancients volcanoes. This material then cooled into formations that we call ‘pipes’. Diamond pipes are being mined today in Botswana, Siberia, South Africa and Tanzania.
16. However, all these formations did not remain intact. Exposed to rain and heat cold for millions of years, many diamond-bearing pipes weathered away. Because the diamonds were so hard, they didn’t break up like the other material. Rather, they were carried along by streams and rivers. When their size or specific gravity was too much for the force of the water, they dropped to the river beds. These are called alluvial deposits, and most of the world’s diamonds come from alluvial mining. The pipe mine in Botswana was discovered by geologists who backtracked from an alluvial deposit along the course of an ancient river.
17. In certain areas of southern Africa, it is believed that some rivers carried diamonds all the way to the Atlantic Ocean, where wave wash deposited them in marine terraces. Some of these terraces are now on dry land, where they are being mined. There is another theory that the diamonds were washed up on the beaches from volcanic pipes on the ocean floor.
18. A diamond pipe is usually composed of a rock-like material called kimberlite, or blue ground. When a diamond pipe is mined, the first step is to dig into it from the surface, like the excavation for a huge building. This is called open-cast mining. It can continue until the hole is too deep for the ore to be brought to the surface easily, but this depth can be 800 to 1000 feet. The Finsch Mine in South Africa, the Williamson Mine in Tanzania and the Orapa Mine in Botswana are open cast mines.
19. When the hole gets too deep, the mine goes underground. Vertical shafts are sunk into the ‘country rock’ away from the pipe. Although there are different methods for underground mining, the basic technique is to drive horizontal tunnels from the shafts into the pipe and then to dig out the diamond-bearing ore from below. This, of course, makes the hole deeper, and the tunnels are driven at successively lower levels until the entire pipe has been mined out, leaving only a hole where the pipe had been. The Big Hole at Kimberley, now the site of a diamond museum, is what remains after the Kimberley Mine was mined out in 1914; now filling with water, it is 1335 feet deep, one of the deepest man-made holes on earth.
20. After the diamond-bearing ore is brought to the surface from either open cast or underground mine, it is put through a long and complex recovery process. The ore is broken up in mills that exert enough force to break the kimberlite, but not the diamonds it contains. Then the broken ore goes through a series of washings, jiggings and screenings that remove much of the waste material. Then what’s left is put into huge tanks that look like mud puddles; the liquid is heavier than water, however, so that the diamonds and other heavier minerals can sink to the bottom in a concentrate while the lighter waste material floats off.
Selling Diamonds (continued)
16. However, all these formations did not remain intact. Exposed to rain and heat cold for millions of years, many diamond-bearing pipes weathered away. Because the diamonds were so hard, they didn’t break up like the other material. Rather, they were carried along by streams and rivers. When their size or specific gravity was too much for the force of the water, they dropped to the river beds. These are called alluvial deposits, and most of the world’s diamonds come from alluvial mining. The pipe mine in Botswana was discovered by geologists who backtracked from an alluvial deposit along the course of an ancient river.
17. In certain areas of southern Africa, it is believed that some rivers carried diamonds all the way to the Atlantic Ocean, where wave wash deposited them in marine terraces. Some of these terraces are now on dry land, where they are being mined. There is another theory that the diamonds were washed up on the beaches from volcanic pipes on the ocean floor.
18. A diamond pipe is usually composed of a rock-like material called kimberlite, or blue ground. When a diamond pipe is mined, the first step is to dig into it from the surface, like the excavation for a huge building. This is called open-cast mining. It can continue until the hole is too deep for the ore to be brought to the surface easily, but this depth can be 800 to 1000 feet. The Finsch Mine in South Africa, the Williamson Mine in Tanzania and the Orapa Mine in Botswana are open cast mines.
19. When the hole gets too deep, the mine goes underground. Vertical shafts are sunk into the ‘country rock’ away from the pipe. Although there are different methods for underground mining, the basic technique is to drive horizontal tunnels from the shafts into the pipe and then to dig out the diamond-bearing ore from below. This, of course, makes the hole deeper, and the tunnels are driven at successively lower levels until the entire pipe has been mined out, leaving only a hole where the pipe had been. The Big Hole at Kimberley, now the site of a diamond museum, is what remains after the Kimberley Mine was mined out in 1914; now filling with water, it is 1335 feet deep, one of the deepest man-made holes on earth.
20. After the diamond-bearing ore is brought to the surface from either open cast or underground mine, it is put through a long and complex recovery process. The ore is broken up in mills that exert enough force to break the kimberlite, but not the diamonds it contains. Then the broken ore goes through a series of washings, jiggings and screenings that remove much of the waste material. Then what’s left is put into huge tanks that look like mud puddles; the liquid is heavier than water, however, so that the diamonds and other heavier minerals can sink to the bottom in a concentrate while the lighter waste material floats off.
Selling Diamonds (continued)
Monday, October 01, 2007
Different Types Of Star Gemstones
In general, star gemstones occur in fewer minerals. In theory, if right conditions were present, almost any mineral could produce asterism.
In a star ruby or sapphire, titanium oxide is exsolved as fine needles of rutile. They orient themselves in three directions, intersecting at 60° and 120° within the same plane producing beautiful stars. The most desirable black star sapphires are those which exhibit the golden star and can be many times more valuable than the more common white-rayed black star sapphires. The asterism of black star sapphire is due to perfectly oriented intergrowth of elongated hematite lamellae. Asterism can be produced in certain types of non-asteriated corundum by moderate heating, if a piece of natural corundum contains enough titanium oxide. Star rubies and sapphires can also be produced by surface diffusion technique, with red and blue being the most common.
Synthetic star corundums by the Verneuil (flame fusion) process are made by adding 0.1-0.3% of titanium oxide to the mixture. The stones are known as Linde stars in the trade and are currently manufactured in several colors, with red and blue being the most common. Identification of synthetic star corundum is not difficult because the needles are usually much smaller than those in the natural stone, and they are more evenly distributed.
Star quartz is sometimes used to imitate star sapphire. The silk usually consists of rutile intersecting in three directions or sillimanite (fibrolite). This may result in a four-rayed star or a six depending upon how the stone is oriented.
Star diopside and star entstatite are two inexpensive stones which are confused with one another. Both display 4-ray stars which meet at almost 90° and one ray is slightly more diffused than the other.
Star beryl is an unusual type. Brown in color and displaying a weak 6-rayed star, it bears a strong resemblance to black star sapphire. The star results from plates of ilmenite and hematite which are oriented in certain positions parallel to the basal plane. These plates also appear to give the stone its dark brown color; if viewed parallel to the plates, clear transparent areas are seen.
The color of star spinel varies from reddish purple to black, with most being quite dark in tone. If the stone is cut so that base is parallel to an octahedron face, a 6-rayed star will be seen; if the stone is cut so that the base is parallel to a cube face, a 4-rayed will be seen. In either case, additional stars will be seen around the girdle. Asterism may also be seen in almandine garnet and moonstone.
In a star ruby or sapphire, titanium oxide is exsolved as fine needles of rutile. They orient themselves in three directions, intersecting at 60° and 120° within the same plane producing beautiful stars. The most desirable black star sapphires are those which exhibit the golden star and can be many times more valuable than the more common white-rayed black star sapphires. The asterism of black star sapphire is due to perfectly oriented intergrowth of elongated hematite lamellae. Asterism can be produced in certain types of non-asteriated corundum by moderate heating, if a piece of natural corundum contains enough titanium oxide. Star rubies and sapphires can also be produced by surface diffusion technique, with red and blue being the most common.
Synthetic star corundums by the Verneuil (flame fusion) process are made by adding 0.1-0.3% of titanium oxide to the mixture. The stones are known as Linde stars in the trade and are currently manufactured in several colors, with red and blue being the most common. Identification of synthetic star corundum is not difficult because the needles are usually much smaller than those in the natural stone, and they are more evenly distributed.
Star quartz is sometimes used to imitate star sapphire. The silk usually consists of rutile intersecting in three directions or sillimanite (fibrolite). This may result in a four-rayed star or a six depending upon how the stone is oriented.
Star diopside and star entstatite are two inexpensive stones which are confused with one another. Both display 4-ray stars which meet at almost 90° and one ray is slightly more diffused than the other.
Star beryl is an unusual type. Brown in color and displaying a weak 6-rayed star, it bears a strong resemblance to black star sapphire. The star results from plates of ilmenite and hematite which are oriented in certain positions parallel to the basal plane. These plates also appear to give the stone its dark brown color; if viewed parallel to the plates, clear transparent areas are seen.
The color of star spinel varies from reddish purple to black, with most being quite dark in tone. If the stone is cut so that base is parallel to an octahedron face, a 6-rayed star will be seen; if the stone is cut so that the base is parallel to a cube face, a 4-rayed will be seen. In either case, additional stars will be seen around the girdle. Asterism may also be seen in almandine garnet and moonstone.
Helvetica
(via The Guardian) Andrew Dickson writes about (Helvetica) typeface and its creators + the movie @ http://arts.guardian.co.uk/art/design/story/0,,2127233,00.html
In pictures: Around the world with Helvetica
Happy birthday, Helvetica
I liked it.
In pictures: Around the world with Helvetica
Happy birthday, Helvetica
I liked it.
How To Buy Gold
Moneyweek explains in detail how to buy gold + the do's and dont's @ http://www.moneyweek.com/file/11428/how-to-buy-gold.html
Useful links:
Goldmoney.com
Kitco.com
Bigcharts.com
Stockcharts.com
Useful links:
Goldmoney.com
Kitco.com
Bigcharts.com
Stockcharts.com
How To Profit From Scarcity
Harvard Business School professor John Quelch writes about the concept of creating the illusion of scarcity + other viewpoints @ http://hbswk.hbs.edu/item/5776.html
Blog: Marketing Know: How
Blog: Marketing Know: How
Odd Man In
Paul Gardner writes about the world and work of Richard Tuttle + other viewpoints @ http://artnews.com/issues/article.asp?art_id=1508
Selling Diamonds
(via Diamond Promotion Service) 6. Specific gravity: The diamond has a specific gravity of 3.52 because a diamond weights a little more than three and half times its equal volume of water. This means that it is a very compact gem. The specific gravity of ruby is 4.03; emerald is 2.74. This characteristic is important both for the location of diamond deposits by prospecting geologists and for the separation of diamonds from the other materials with which they are found in nature.
7. Thermal expansion: Many minerals expand and contract with heat and cold. The diamond doesn’t, and therefore is not affected by changes in temperature. A diamond will burn at 1444ºF, which is the range of a blowtorch. It will not melt until the heat reaches 6642ºF. This explains why diamonds can remain unscathed in even the most disastrous of fires.
8. Conductivity: Diamonds conduct very little heat. Most diamonds are non-conductors of electricity. Conductivity is a characteristic more important for industrial diamonds than for gems.
Where Diamonds Are Found
9. Diamonds were first found in India, more than 2500 years ago, along the banks and beds of ancient rivers. Golconda, which has always been a symbol for fabulous riches, was one of the great diamond-producing districts. Travelers brought diamonds from India into the Mediterranean world; diamonds are mentioned in the Old Testament, and they were well-known in Greek and Roman times. For many centuries India was the only source of diamonds, but today it accounts for less than one-tenth of one percent of the world’s natural diamond production.
10. Diamonds were discovered in Brazil in the 18th century, and this new source of supply helped meet the demand for diamonds by the increasingly affluent middle class in Europe. (Diamond had also been found in the East Indies by this time, but in very small numbers). South American diamonds, from Brazil, Guyana and Venezuela, account for a little more than one percent of the world’s production today.
11. The first diamond in South Africa was discovered in 1866, and the mines opened in the next 20 years made a tremendous increase in the supply of diamonds. While South African diamonds were treasured by princes and potentates, they also made it possible for almost every girl in Europe and America to have a diamond engagement ring. South Africa and South-West Africa (where diamonds were discovered in 1908) today account for about 20 percent of the world’s natural diamond production.
12. Later diamonds were discovered in other parts of Africa, and that continent is the largest producer of diamonds. Republic of Zaire (DR Congo) is the largest single diamond producing country, accounting for about 35 percent of the world’s production; but most of its diamonds are industrials rather than gems. Angola, the Central African Republic, Congo (Brazzaville), Ghana, Guinea, the Ivory Coast, Lesotho, Liberia, Sierra Leone and Tanzania together account for about 23 percent of the world’s diamonds. The newest of all diamond mines was opened in the new republic of Botswana in 1971.
13. Diamonds were discovered in eastern Siberia within our own time, in the Yakutia district above the Artic Circle. The Russians do not release their production figures, but estimates are that Russian diamonds account for about 20 percent of the annual world production today.
14. Diamonds have been found in many parts of the United States, but never in sufficient concentration for economic mining. At Murfreesboro, Arkansas, there is a diamond pipe which is worked by tourists, for fun—and they find diamonds.
Selling Diamonds (continued)
7. Thermal expansion: Many minerals expand and contract with heat and cold. The diamond doesn’t, and therefore is not affected by changes in temperature. A diamond will burn at 1444ºF, which is the range of a blowtorch. It will not melt until the heat reaches 6642ºF. This explains why diamonds can remain unscathed in even the most disastrous of fires.
8. Conductivity: Diamonds conduct very little heat. Most diamonds are non-conductors of electricity. Conductivity is a characteristic more important for industrial diamonds than for gems.
Where Diamonds Are Found
9. Diamonds were first found in India, more than 2500 years ago, along the banks and beds of ancient rivers. Golconda, which has always been a symbol for fabulous riches, was one of the great diamond-producing districts. Travelers brought diamonds from India into the Mediterranean world; diamonds are mentioned in the Old Testament, and they were well-known in Greek and Roman times. For many centuries India was the only source of diamonds, but today it accounts for less than one-tenth of one percent of the world’s natural diamond production.
10. Diamonds were discovered in Brazil in the 18th century, and this new source of supply helped meet the demand for diamonds by the increasingly affluent middle class in Europe. (Diamond had also been found in the East Indies by this time, but in very small numbers). South American diamonds, from Brazil, Guyana and Venezuela, account for a little more than one percent of the world’s production today.
11. The first diamond in South Africa was discovered in 1866, and the mines opened in the next 20 years made a tremendous increase in the supply of diamonds. While South African diamonds were treasured by princes and potentates, they also made it possible for almost every girl in Europe and America to have a diamond engagement ring. South Africa and South-West Africa (where diamonds were discovered in 1908) today account for about 20 percent of the world’s natural diamond production.
12. Later diamonds were discovered in other parts of Africa, and that continent is the largest producer of diamonds. Republic of Zaire (DR Congo) is the largest single diamond producing country, accounting for about 35 percent of the world’s production; but most of its diamonds are industrials rather than gems. Angola, the Central African Republic, Congo (Brazzaville), Ghana, Guinea, the Ivory Coast, Lesotho, Liberia, Sierra Leone and Tanzania together account for about 23 percent of the world’s diamonds. The newest of all diamond mines was opened in the new republic of Botswana in 1971.
13. Diamonds were discovered in eastern Siberia within our own time, in the Yakutia district above the Artic Circle. The Russians do not release their production figures, but estimates are that Russian diamonds account for about 20 percent of the annual world production today.
14. Diamonds have been found in many parts of the United States, but never in sufficient concentration for economic mining. At Murfreesboro, Arkansas, there is a diamond pipe which is worked by tourists, for fun—and they find diamonds.
Selling Diamonds (continued)
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