Saturday, October 06, 2007
Sign Here!
Mary Haus writes about artist's signature (s), (especially when you are famous) + the power of signature (s) (which may perceived) as self-expression + the adverstising link + other viewpoints @ http://artnews.com/issues/article.asp?art_id=1557
Selling Diamonds
(via Diamond Promotion Service) The Beauty Of A Diamond: 36. The beauty of a diamond comes from the light that passes through it or is reflected from it. Light is something that we take for granted, without recognizing that it is made up of countless rays shooting in all directions. To understand how light makes the beauty of a diamond, we have to think of it in terms of individual rays.
When a ray of light strikes a diamond, 18 percent is reflected allowing 82 percent to enter the stone. As a ray of light enters the diamond, it changes direction according to the refractive index and then keeps going until it strikes the inside of another facet. If it strikes that facet within the critical angle (24.1º), it goes on through and leaves the diamond. Otherwise, it bounces off in a new direction, still within the stone.
The proportioning of the diamond and the cutting of the facets to precise angles are designed so that as much light as possible can go into the stone from the top, bounce around inside, and then come back out the top again with brilliance, fire and scintillation. A diamond whose proportions are too deep will leak light through the facets below the girdle. One whose proportions are too shallow will also leak light, and it may have a fish eye dead spot on top.
The larger the diamond, of course, the larger the top surface area that can admit light. However, small diamonds are just as efficient in their handling of light and produce just as beautiful an effect.
37. Brilliance. Brilliance, fire and scintillation are often confused. In the strictest sense, brilliance is the intensity of the reflections of white light from the diamond that meet the eye when we look down into it. These are the internal reflections of light from the inside surfaces of the facets below the girdle. Because it is so hard, the diamond takes a high polish and so gives off more brilliance surface reflections than does any other gem. So the diamond’s brilliance comes from its internal and external reflections of light.
38. Fire. The diamond’s ability to break up a ray of white light into all colors of the spectrum gives it fire. The dispersion is greater than any other precious gem. The width of this dispersion, the amount of fire, is least when a ray of light leaves the diamond at an angle (24.1°) near the perpendicular. So the 32 facets between the girdle and the table are placed to take maximum advantage of the diamond’s power of dispersion, to give the diamond the most fire possible.
39. Scintillation. The nursery rhyme sings, ‘Twinkle, twinkle, little star…like a diamond in the sky.’ Scintillation is that twinkling or flashing of light from the facets of a diamond as it moves. This depends primarily on three things: the sizes of the pavilion facets below the girdle; the number of facets visible to the eye as the diamond moves; and the high polish or luster of the facets reflecting the light. Scintillation explains why diamonds are so much more beautiful when they are in motion while being worn than they are at rest. Moving either the eye or the light source will also cause scintillation.
Selling Diamonds (continued)
When a ray of light strikes a diamond, 18 percent is reflected allowing 82 percent to enter the stone. As a ray of light enters the diamond, it changes direction according to the refractive index and then keeps going until it strikes the inside of another facet. If it strikes that facet within the critical angle (24.1º), it goes on through and leaves the diamond. Otherwise, it bounces off in a new direction, still within the stone.
The proportioning of the diamond and the cutting of the facets to precise angles are designed so that as much light as possible can go into the stone from the top, bounce around inside, and then come back out the top again with brilliance, fire and scintillation. A diamond whose proportions are too deep will leak light through the facets below the girdle. One whose proportions are too shallow will also leak light, and it may have a fish eye dead spot on top.
The larger the diamond, of course, the larger the top surface area that can admit light. However, small diamonds are just as efficient in their handling of light and produce just as beautiful an effect.
37. Brilliance. Brilliance, fire and scintillation are often confused. In the strictest sense, brilliance is the intensity of the reflections of white light from the diamond that meet the eye when we look down into it. These are the internal reflections of light from the inside surfaces of the facets below the girdle. Because it is so hard, the diamond takes a high polish and so gives off more brilliance surface reflections than does any other gem. So the diamond’s brilliance comes from its internal and external reflections of light.
38. Fire. The diamond’s ability to break up a ray of white light into all colors of the spectrum gives it fire. The dispersion is greater than any other precious gem. The width of this dispersion, the amount of fire, is least when a ray of light leaves the diamond at an angle (24.1°) near the perpendicular. So the 32 facets between the girdle and the table are placed to take maximum advantage of the diamond’s power of dispersion, to give the diamond the most fire possible.
39. Scintillation. The nursery rhyme sings, ‘Twinkle, twinkle, little star…like a diamond in the sky.’ Scintillation is that twinkling or flashing of light from the facets of a diamond as it moves. This depends primarily on three things: the sizes of the pavilion facets below the girdle; the number of facets visible to the eye as the diamond moves; and the high polish or luster of the facets reflecting the light. Scintillation explains why diamonds are so much more beautiful when they are in motion while being worn than they are at rest. Moving either the eye or the light source will also cause scintillation.
Selling Diamonds (continued)
Friday, October 05, 2007
Myanmar's Rubies - Bloody Color, Bloody Business
Carmel Crimmins writes about international outrage over the Burmese generals' brutal crackdown on pro-democracy rallies + possible trade ban by the European Union on Myanmar's gemstones, a leading export earner in the impoverished country.
If it works, it's going to be conflict rubies. If the trade sanctions work (I wish them good luck) then ruby prices will definitely go up + there will be behind the scene deals without disclosure. There are people who are addicted to rubies and they may not care so much about human rights abuses in Burma. They have deep pockets, a big safe + no memory. But if the consumers really care for the Burmese people, and if they stop buying rubies it's going to be Catch-22. There will be job losses, many traders who specialize in Burmese rubies may go out of business +++++. What are the alternatives? There are a few ruby producing mines scattered around the world but the productions are sporadic + qualites vary + they may not be suitable for treatment (s) in order to enhance the color / clarity. The issue is will it work. We don't have the same compliance mechanism like the diamond industry. The colored gemstone industry is fracture-filled with special interest (s) groups. They have one story for the world and media and another for the trade. Let's watch and wait.
More info @ http://www.reuters.com/article/topNews/idUSMAN5177620071004?sp=true
If it works, it's going to be conflict rubies. If the trade sanctions work (I wish them good luck) then ruby prices will definitely go up + there will be behind the scene deals without disclosure. There are people who are addicted to rubies and they may not care so much about human rights abuses in Burma. They have deep pockets, a big safe + no memory. But if the consumers really care for the Burmese people, and if they stop buying rubies it's going to be Catch-22. There will be job losses, many traders who specialize in Burmese rubies may go out of business +++++. What are the alternatives? There are a few ruby producing mines scattered around the world but the productions are sporadic + qualites vary + they may not be suitable for treatment (s) in order to enhance the color / clarity. The issue is will it work. We don't have the same compliance mechanism like the diamond industry. The colored gemstone industry is fracture-filled with special interest (s) groups. They have one story for the world and media and another for the trade. Let's watch and wait.
More info @ http://www.reuters.com/article/topNews/idUSMAN5177620071004?sp=true
The Devil And Daniel Webster
Greatest Opening Film Lines (The Devil and Daniel Webster - 1941):
You're only wasting your time writing speeches like that. Why worry about the people and their problems? Think of your own.
I liked this one.
You're only wasting your time writing speeches like that. Why worry about the people and their problems? Think of your own.
I liked this one.
Instant Online Demographic Information
Here is an interesting link www.targetmailers.com which helps jewelers to pull a list of prospects in their area based on household income, net worth, gender, age, credit card usage and so on. I think this may work only in the US, but other countries could learn from the concept.
Why The Gold Market Is An Investor's Best Friend
(via Moneyweek) Martin Denholm explains the concept + the dos and dont's + other viewpoints @ http://www.moneyweek.com/file/33065/why-the-gold-market-is-an-investors-best-friend.html
Diamonds And Flowers
(via JCK) Here is an interesting article on diamond vs. flowers by Ben Janowski. The entire column is worth a read. http://jckonline.com/article/CA6486021.html
Basel II and Dave’s Brilliant ‘Financial Striptease’
Chaim Even-Zohar writes about the impact of the Basel II bank capital adequacy requirements on diamantaires businesses + the Dave Lapa (Belgium diamantaire) story + other viewpoints @ http://www.idexonline.com/portal_FullEditorial.asp
The Top Ten - Summer 2004
Milton Esterow writes about unique collectors + the things top collectors should have (deep pockets, big closets, no memory) + other viewpoints @ http://artnews.com/issues/article.asp?art_id=1575
The ARTnews 200
by The Editors of ARTnews
Annual (2004) list of the world’s top collectors @ http://artnews.com/issues/article.asp?art_id=1574
The ARTnews 200
by The Editors of ARTnews
Annual (2004) list of the world’s top collectors @ http://artnews.com/issues/article.asp?art_id=1574
Selling Diamonds
(via Diamond Promotion Service) 31. Cleaving. When a rough diamond is to be divided ‘with the grain’, it is cleaved. The cleaver sets the stone in a dop, or holder, and he uses another diamond to scratch a groove along the division line. Then he inserts a square-edged knife into the groove and taps it back sharply with a mallet. If everything is right, the stone splits cleanly. If the division line has not been placed properly (or followed accurately), the diamond can shatter.
Cleaving is considered the most dramatic of all the steps in diamond cutting because the whole future of the diamond rides on that one tap of the mallet. When the stone is a large and important one, that can mean hundreds of thousands of dollars.
32. Bruting. The next cutting step is bruting, which is also called rounding or girdling. This forms the girdle, which is the basic dimension of the finished diamond.
The bruter sets the stone in a dop and fixes the dop in a lathe which spins at high speed. Using another diamond set in the end of a long bruting stick, he gradually grinds off the corners until the spinning diamond is round at its thickest part. In the process he partially rounds the diamond in the bruting stick, and this is later put on the lathe to finish its own bruting.
Diamonds finished in the round or brilliant cut go through the bruting step in this way. Those finished in the oval, marquise and pear shape cut usually go through the same step, but by a slightly different process. Emerald-cut diamonds have their girdles formed in a different way.
33. Blocking. The primary facets of the diamond are ground onto it by the blocker. He works with a cast iron plate called a scaife, impregnated with oil and diamond dust, which revolves like the turntable of a phonograph. He sets the diamond in a holder and lowers it onto the spinning plate, and he has to change its position for every facet.
The table, which is the largest facet of the diamond, is usually the surface formed when the stone is sawed or cleaved. The girdle has been formed with its plane parallel to the table. Now the blocker grinds a facet between the table and the girdle at an angle of 34.5º to the plane of the girdle. Then he grinds two more facets, one on either side exactly between the first two. These are called crown or bezel facets. Then he turns the stone over and grinds four corresponding pavilion facets below the girdle, each 41º to the girdle plane.
In the second stage of blocking, he grinds four more bezel facets above the girdle, each exactly between two of the first four facets, and four more pavilion facets to correspond. It takes a long time for each facet to be ground, and the blocker has to check the process constantly to see that not too much is being ground away on any one facet.
At this point the diamond looks like the familiar gem. It has 17 facets—8 bezel facets and the table above the girdle, and 8 pavilion facets meeting in a point below the girdle. The blocker then grinds off the point in a tiny culet facet that is exactly parallel to the table and the plane of the girdle.
For diamonds that are 50 to the carat or smaller, this can be the end of the line. Such diamonds, with only 18 facets, are called single cuts.
34. Brillianteering. This is the final cutting step for 58-facet diamonds, which are called full cuts. The brillianteerer works with the same scaife that the blocker used, and he cuts the last 40 facets.
Of these, 24 are placed in threes between the 8 bezel facets; two extend up from the girdle, and the third extends down from the table. The other 16 are placed in pairs between the pavilion facets, extending down from the girdle. As each new facet is cut, of course, it changes the shape of the adjoining facets.
Cutting is a long, exacting and expensive process. Cutters are skilled craftsmen who must use the judgment gained by long years of experience to bring out the full beauty of a diamond. Automation is beginning in the cutting industry, with smaller diamonds.
35. Shapes. The finished diamond may have any of several shapes, each of which is also called a cut. The brilliant cut, or round, is the most popular of all diamond shapes. Round diamonds can be finished, with 17 or 18 facets, in sizes so small that they will run more than 200 to the carat. This type of brilliant is known as single or eight cut.
The oval cut, as its name implies, is an elongated round. The marquise cut is rounded in the middle and pointed at each end, like a weaver’s shuttle. The pear shape is rounded at one end and pointed at the other. The heart shape is essentially a pear shape with a notch in the rounded end.
The proportion of length to width may vary within each of these ‘fancy’ cuts so that is possible, for example, to have both ‘thin’ pear shapes and ‘fat’ pear shapes. Each of these cuts has the same 58 facets as the brilliant cut, but the shapes of the facets are different. Some larger diamonds in these cuts have girdles thick enough for additional facets around them.
The emerald cut (and its companion, the square cut) also has 58 facets, all of which are very close to rectangular. There are 24 facets and the table above the girdle, and 24 facets and the culet below; the remaining 8 facets are around the girdle.
Any of these shapes may be used as the solitaire or principal diamond in an engagement ring. They may also be used in other types of jewelry. The advantage of the fancy shapes for the cutter is that they usually can be cut from irregular pieces of rough with less loss of weight than a round can be cut. Their advantage for the customer is that they tend to look larger than a round diamond of the same weight.
But these are not the only shapes of diamonds being cut today. For the most part, the others are small diamonds which are set as side stones in rings or as secondary stones in other types of jewelry. Usually they are cut in these shapes to get maximum weight out of irregular small pieces of rough.
The baguette is thin and rectangular, like an emerald cut with 17 facets. The tapered baguette is wider at one end than the other, like a tall trapezoid. The trapeze follows the standard trapezoid shape, with the long sides parallel and the short sides angled toward each other.
The triangle is a three-sided stone, as the name implies. The kite shape looks like a kite, or two triangles of different sizes. The lozenge is like the diamond pip on a playing card, or two triangles of equal sizes. The half moon has the shape of a crescent.
Selling Diamonds (continued)
Cleaving is considered the most dramatic of all the steps in diamond cutting because the whole future of the diamond rides on that one tap of the mallet. When the stone is a large and important one, that can mean hundreds of thousands of dollars.
32. Bruting. The next cutting step is bruting, which is also called rounding or girdling. This forms the girdle, which is the basic dimension of the finished diamond.
The bruter sets the stone in a dop and fixes the dop in a lathe which spins at high speed. Using another diamond set in the end of a long bruting stick, he gradually grinds off the corners until the spinning diamond is round at its thickest part. In the process he partially rounds the diamond in the bruting stick, and this is later put on the lathe to finish its own bruting.
Diamonds finished in the round or brilliant cut go through the bruting step in this way. Those finished in the oval, marquise and pear shape cut usually go through the same step, but by a slightly different process. Emerald-cut diamonds have their girdles formed in a different way.
33. Blocking. The primary facets of the diamond are ground onto it by the blocker. He works with a cast iron plate called a scaife, impregnated with oil and diamond dust, which revolves like the turntable of a phonograph. He sets the diamond in a holder and lowers it onto the spinning plate, and he has to change its position for every facet.
The table, which is the largest facet of the diamond, is usually the surface formed when the stone is sawed or cleaved. The girdle has been formed with its plane parallel to the table. Now the blocker grinds a facet between the table and the girdle at an angle of 34.5º to the plane of the girdle. Then he grinds two more facets, one on either side exactly between the first two. These are called crown or bezel facets. Then he turns the stone over and grinds four corresponding pavilion facets below the girdle, each 41º to the girdle plane.
In the second stage of blocking, he grinds four more bezel facets above the girdle, each exactly between two of the first four facets, and four more pavilion facets to correspond. It takes a long time for each facet to be ground, and the blocker has to check the process constantly to see that not too much is being ground away on any one facet.
At this point the diamond looks like the familiar gem. It has 17 facets—8 bezel facets and the table above the girdle, and 8 pavilion facets meeting in a point below the girdle. The blocker then grinds off the point in a tiny culet facet that is exactly parallel to the table and the plane of the girdle.
For diamonds that are 50 to the carat or smaller, this can be the end of the line. Such diamonds, with only 18 facets, are called single cuts.
34. Brillianteering. This is the final cutting step for 58-facet diamonds, which are called full cuts. The brillianteerer works with the same scaife that the blocker used, and he cuts the last 40 facets.
Of these, 24 are placed in threes between the 8 bezel facets; two extend up from the girdle, and the third extends down from the table. The other 16 are placed in pairs between the pavilion facets, extending down from the girdle. As each new facet is cut, of course, it changes the shape of the adjoining facets.
Cutting is a long, exacting and expensive process. Cutters are skilled craftsmen who must use the judgment gained by long years of experience to bring out the full beauty of a diamond. Automation is beginning in the cutting industry, with smaller diamonds.
35. Shapes. The finished diamond may have any of several shapes, each of which is also called a cut. The brilliant cut, or round, is the most popular of all diamond shapes. Round diamonds can be finished, with 17 or 18 facets, in sizes so small that they will run more than 200 to the carat. This type of brilliant is known as single or eight cut.
The oval cut, as its name implies, is an elongated round. The marquise cut is rounded in the middle and pointed at each end, like a weaver’s shuttle. The pear shape is rounded at one end and pointed at the other. The heart shape is essentially a pear shape with a notch in the rounded end.
The proportion of length to width may vary within each of these ‘fancy’ cuts so that is possible, for example, to have both ‘thin’ pear shapes and ‘fat’ pear shapes. Each of these cuts has the same 58 facets as the brilliant cut, but the shapes of the facets are different. Some larger diamonds in these cuts have girdles thick enough for additional facets around them.
The emerald cut (and its companion, the square cut) also has 58 facets, all of which are very close to rectangular. There are 24 facets and the table above the girdle, and 24 facets and the culet below; the remaining 8 facets are around the girdle.
Any of these shapes may be used as the solitaire or principal diamond in an engagement ring. They may also be used in other types of jewelry. The advantage of the fancy shapes for the cutter is that they usually can be cut from irregular pieces of rough with less loss of weight than a round can be cut. Their advantage for the customer is that they tend to look larger than a round diamond of the same weight.
But these are not the only shapes of diamonds being cut today. For the most part, the others are small diamonds which are set as side stones in rings or as secondary stones in other types of jewelry. Usually they are cut in these shapes to get maximum weight out of irregular small pieces of rough.
The baguette is thin and rectangular, like an emerald cut with 17 facets. The tapered baguette is wider at one end than the other, like a tall trapezoid. The trapeze follows the standard trapezoid shape, with the long sides parallel and the short sides angled toward each other.
The triangle is a three-sided stone, as the name implies. The kite shape looks like a kite, or two triangles of different sizes. The lozenge is like the diamond pip on a playing card, or two triangles of equal sizes. The half moon has the shape of a crescent.
Selling Diamonds (continued)
Thursday, October 04, 2007
Oil Crash Movie
(via Doors Report) After Al Gore's 'An Inconvenient Truth' comes another blockbuster: 'Crude Awakening: The Oil Crash'.
This film tells the story of 'how our civilization's addiction to oil puts it on a collision course with geology'. A succession of oil experts in crumpled suits come to a startling, but logical conclusion: our industrial society, built on cheap and readily available oil, must be completely re-imagined and overhauled. Or....
Useful link:
http://www.oilcrashmovie.com/film.html
This film tells the story of 'how our civilization's addiction to oil puts it on a collision course with geology'. A succession of oil experts in crumpled suits come to a startling, but logical conclusion: our industrial society, built on cheap and readily available oil, must be completely re-imagined and overhauled. Or....
Useful link:
http://www.oilcrashmovie.com/film.html
Panyu, China
Panyu, located in the city of Guangzhou, hosts more than 300 jewelry-manufacturing companies. According to government statistics, jewelry exports from Hong Kong in 2006 totaled $5.49 billion, of which $1.16 billion worth of jewelry was manufactured in Panyu.
Why Gold Is Better Than Paper Money
(via Moneyweek) Bill Bonner of Daily Reckoning writes about investing in gold + other viewpoints @ http://www.moneyweek.com/file/12195/why-gold-is-better-than-paper-money.html
Classics Of Everyday Design
(via The Guardian) Jonathan Glancey's everyday design classics @
Jonathan Glancey's classics of everyday design
Classics of everyday design No 2
Classics of everyday design No 3
Classics of everyday design No 4
Classics of everyday design No 5
I liked it.
Jonathan Glancey's classics of everyday design
Classics of everyday design No 2
Classics of everyday design No 3
Classics of everyday design No 4
Classics of everyday design No 5
I liked it.
The Quintessential Designer
(via The Guardian) Ian Sample writes about Jonathan Ive, the genius behind iBook and iMac, and latterly the ubiquitous iPod range + his rise to public prominence with the return to Apple of ebullient chief executive Steve Jobs + other viewpoints @ http://arts.guardian.co.uk/art/design/story/0,,1992361,00.html
The Cult Of Leica
Anthony Lane writes about Leica camera + the brand and its evolution since 1925 + the major-league names that were associated with the Leica brand + other viewpoints @ http://www.newyorker.com/reporting/2007/09/24/070924fa_fact_lane
Moving Mountains, Walking On Water
Ann Landi writes about Earthworks, Land Art, or Earth Art by major artists like Robert Smithson, Walter De Maria, James Turrell, and Michael Heizer + newcomers and the impact + other viewpoints @ http://artnews.com/issues/article.asp?art_id=1540
Selling Diamonds
(via Diamond Promotion Service) Diamond Cutting: 28. The beauty of a gem diamond depends on the way it handles light. Diamond cutting unlocks this beauty.
The ancient Indian lapidaries learned that the surfaces of a diamond could be polished by rubbing another diamond against them. This enabled the diamond to reflect more light, and in ancient times the diamond was called the Venus stone because of its brightness. In the 15th century important discoveries were made which resulted in even brighter stones through the grinding of additional facets or planes. More than two centuries later a Venetian cutter named Peruzzi invented the 58-facet form for round diamonds that is basic to today’s cutting. In 1919 Marcel Tolkowsky, a physicist, developed the relationship of facet angles that is considered ideal for modern cutting.
Antwerp and Israel are the largest diamond cutting centers in the world. Other important centers are Amsterdam, United States, India, West Germany and South Africa. Cutting is also done on a lesser scale in England, Puerto Rico, Russia, France and Portugal. Each center has gradually, over the years, come to specialize in cutting a particular quality of diamonds. Cleavages and chips are, in the main, worked in Antwerp; stones and shapes in the United States; and melee in Amsterdam, Israel and West Germany.
29. Marking. The first step in diamond cutting is an examination of the rough stone by the planner, usually a master cutter. Using his loupe, or magnifying glass, he studies every aspect of the stone. For very large diamonds, this study can go on for months, but for the average diamond the study is done in a few minutes. Nevertheless, every diamond must be studied, no matter how small it is.
The planner has to be conscious of two factors. Under normal circumstances, a rough diamond loses more than half its weight in the cutting process; so the planner has to determine the finished shape that will retain as much weight as possible. Most diamonds contain natural imperfections, or inclusions; so that planner has to position the finished shape and direct the cutting so that as many inclusions as possible can be ground away and the remaining inclusions will offer minimum interference with the passage of light through the stone. Sometimes, to eliminate a major inclusion, the planner will have a stone cut smaller than it could be.
Then he marks the diamond with India ink to indicate how the cutting will go. The principal mark shows how the stone must be divided. An octahedron crystal is usually divided just above the middle, and both parts are cut into round diamonds. An irregular piece of rough may be divided into several pieces, and each piece will be cut into a finished gem. When a piece of rough is already close to the shape of a finished gem, it may not be divided at all but just ground down into the finished shape.
30. Sawing. Most octahdedron crystals, and many irregular shapes, are divided ‘against the grain’, and so they are sawed. Only diamond will cut diamond; therefore, the saw is a thin disk of phosphor bronze, its edge coated with a paste of oil and diamond dust. The saw is mounted vertically and spins at high speed. The diamond is set into a clamp so that it can be lowered against the saw’s edge in the plane along which it must be divided. Gravity keeps the stone against the saw while it is being cut.
It takes hours to cut through even a small diamond. However, one sawyer can handle a batter of saws, checking each stone at intervals to ensure that is being sawed correctly. The deviation of even a hair can affect the finished gem.
Selling Diamonds (continued)
The ancient Indian lapidaries learned that the surfaces of a diamond could be polished by rubbing another diamond against them. This enabled the diamond to reflect more light, and in ancient times the diamond was called the Venus stone because of its brightness. In the 15th century important discoveries were made which resulted in even brighter stones through the grinding of additional facets or planes. More than two centuries later a Venetian cutter named Peruzzi invented the 58-facet form for round diamonds that is basic to today’s cutting. In 1919 Marcel Tolkowsky, a physicist, developed the relationship of facet angles that is considered ideal for modern cutting.
Antwerp and Israel are the largest diamond cutting centers in the world. Other important centers are Amsterdam, United States, India, West Germany and South Africa. Cutting is also done on a lesser scale in England, Puerto Rico, Russia, France and Portugal. Each center has gradually, over the years, come to specialize in cutting a particular quality of diamonds. Cleavages and chips are, in the main, worked in Antwerp; stones and shapes in the United States; and melee in Amsterdam, Israel and West Germany.
29. Marking. The first step in diamond cutting is an examination of the rough stone by the planner, usually a master cutter. Using his loupe, or magnifying glass, he studies every aspect of the stone. For very large diamonds, this study can go on for months, but for the average diamond the study is done in a few minutes. Nevertheless, every diamond must be studied, no matter how small it is.
The planner has to be conscious of two factors. Under normal circumstances, a rough diamond loses more than half its weight in the cutting process; so the planner has to determine the finished shape that will retain as much weight as possible. Most diamonds contain natural imperfections, or inclusions; so that planner has to position the finished shape and direct the cutting so that as many inclusions as possible can be ground away and the remaining inclusions will offer minimum interference with the passage of light through the stone. Sometimes, to eliminate a major inclusion, the planner will have a stone cut smaller than it could be.
Then he marks the diamond with India ink to indicate how the cutting will go. The principal mark shows how the stone must be divided. An octahedron crystal is usually divided just above the middle, and both parts are cut into round diamonds. An irregular piece of rough may be divided into several pieces, and each piece will be cut into a finished gem. When a piece of rough is already close to the shape of a finished gem, it may not be divided at all but just ground down into the finished shape.
30. Sawing. Most octahdedron crystals, and many irregular shapes, are divided ‘against the grain’, and so they are sawed. Only diamond will cut diamond; therefore, the saw is a thin disk of phosphor bronze, its edge coated with a paste of oil and diamond dust. The saw is mounted vertically and spins at high speed. The diamond is set into a clamp so that it can be lowered against the saw’s edge in the plane along which it must be divided. Gravity keeps the stone against the saw while it is being cut.
It takes hours to cut through even a small diamond. However, one sawyer can handle a batter of saws, checking each stone at intervals to ensure that is being sawed correctly. The deviation of even a hair can affect the finished gem.
Selling Diamonds (continued)
Wednesday, October 03, 2007
Bangkok Gems And Jewelry Fair
According to Vichai Assarasakorn, chief executive of the BGJF organizing committee, the show went beyond expectation in the wake of adverse impacts like the sluggish global economy and, more recently, the U.S. sub-prime loan fallout + more than 10 national groups from such markets as Europe, India, Russia and the United States met with exhibitors at the fair.
According to Thailand's Minister of Commerce Krik-krai Jirapaet, gems and jewelry exports last year exceeded $3.6 billion, up 12.7 percent from the previous year. In the first seven months of this year, gems and jewelry exports increased 5.41 percent year-on-year to $2.18 billion.
The next edition of the Bangkok Gems and Jewelry Fair will take place from Feb. 27-March 2, 2008.
According to Thailand's Minister of Commerce Krik-krai Jirapaet, gems and jewelry exports last year exceeded $3.6 billion, up 12.7 percent from the previous year. In the first seven months of this year, gems and jewelry exports increased 5.41 percent year-on-year to $2.18 billion.
The next edition of the Bangkok Gems and Jewelry Fair will take place from Feb. 27-March 2, 2008.
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