JCK New Delhi 2008, the jewelry exhibition is catching up in the country on a great pace and is now all geared up to brighten Delhi in July at Pragati Maidan. The show will see the best of jewelry manufacturers, wholesalers, exporters and retailers gather and explore huge business opportunity offered through this platform. The exhibition has set new benchmarks in the field of Jewellery trade fairs in India since its inception in 2006 and is on the way of scaling bigger heights year after year.
JCK New Delhi 2008 is backed by Delhi Jewellers Association, World Gold Council and GJEPC and offers a strict business-to-business platform for the most suitable business environment to trade. The exhibition is not only classy & luxurious but is also very meticulously planned out. There are well segmented pavilions of Gold & Fine Jewelry, Diamond & Fine Jewelry, Gem Stones & Gemstone Jewelry, Laboratories, Silver Jewelry & Hollowware, Machinery and Tools for focused exhibition browsing. The show will bind the traders from across India along with various other countries, and would also deliver a world class ambience and a show experience to remember!
Learn more by visiting www.jcknewdelhi.com or click here to contact JCK New Delhi 2008.
Well supported by the industry, the show features 250 prominent exhibitors both in national and international league like:
Aashna Diamonds, Abhay Navinchandra, ACPL, Amore Jewels Pvt. Ltd., Apple Gems International, A'Star Jewellery, Bhavani Jewels, Ciemme Jewels Ltd., CVM Exports, Diam Circle Mfg. Pvt. Ltd, European Gemological Laboratory Pvt. Ltd., Forever Precious Jewellery & Diamonds Ltd., Gitanjali Gems Ltd., GDK Jewels Pvt. Ltd., GIE Gold Creations Pvt. Ltd., Golkunda Diamonds & Jewellery Ltd., H K Jewellers, Hammer Plus Jewellery Pvt. Ltd., Hariprasad Gopikrishna Jewellers Pvt. Ltd., IGI, J.B. & Brothers, Jindal Diamonds and Gems Pvt. Ltd., Kantilal Chhotalal, KGK Creations (India) Pvt. Ltd., Kothari Jewels, Kundan Hut, M.R. Chains Pvt. Ltd., Majestic Gems, Nolkha Jewellers, Osia Gems, P. Manoharlal Jewellers & Exporters, Panache Exports Pvt. Ltd., Pranda Jewellery Pvt. Ltd., Ridhi Sidhi Gems, RMC Gems India Limited, Sanghavi Exports International Pvt. Ltd., Shanti Gold, Sheetal Manufacturing, Shivin Jewellers, Solitaire Diam, Sri Balaji Jewellers & Exporters, Suashish Diamonds Limited, S K Chains, Shashwat Jewels, Uni-Design Jewellery India Pvt. Ltd., Vikas Chain, Laxmi Dia Jewel Pvt. Ltd., Ary Gold Designers, GIA India, IDL, IGL, Reliance Money Ltd., Ashlyn Chemunnoor Instruments Pvt. Ltd., Nickunj Eximp Entp P Ltd., Citizen Scale (I) Pvt. Ltd., N Jewellery Techniques Pvt. Ltd., Tache, B&S Antwerp NV, Baymonte, Colombian Stone Co., Ltd., SIDRA S.A.R.L., Siam Shine Star Co. Ltd., Bassano Collection, Jewels & Nuggets and many, many more!
This year JCK New Delhi brings together exhibitors covering the entire jewelry segment & offers a complete range in trends and prices to ensure a reason for our visitors from every segment including organized, family owned, large and small buyers to do profitable business at the show. To ensure that the platform is approachable, various customized marketing initiatives and efforts are being taken for each segment simultaneously, consequently facilitating activities to meet the business objectives of all the exhibitors. Many programs are also undertaken to maximize business transaction possibilities for the exhibitors at the show. Minutest details are being given extra care to deliver a flawless show this time.
Some key show highlights:
~Features an wide variety from each jewelry category - gemstones, diamonds, gold, fine jewelry, high Italian jewelry, machinery & tools, silver jewelry and CZ jewelry to cater to all the retailer's need.
~Special Delhi Pavilion to showcase Delhi manufactures and wholesalers.
~Features unique exhibitor offers for the visitors exclusively for JCK New Delhi 2008.
~A true national scale exhibition covering with enhanced international participation from Thailand, Dubai, Italy, Belgium, Turkey, Lebanon, US, Japan and so on.
~No pre-registration fee for Visitors to encourage the trade to approach keeping the onsite registration fee to Rs. 1000!
~Offers desired serious business environment for pure business and transactions.
~Planned in July, which is the most favorable month for Retailers to buy and browse through the opportunities [Source: as per the survey conducted by the research agency, Facts & Opinion].
Reed Exhibitions Chief Operating Officer, Mr. Mandeep Singh added "We are 90% sold out in the month of April already with prominent players. Also, to pull buyers of various capacities we have special buyers proposition from the exhibitors only available in the 4 days of JCK New Delhi. We also have various campaigns running like Progressive Buyers CRM program to acknowledge leading buyers per city on certain parameters gaining popularity, along with Foot Soldier activity encompassing 9 cities ensuring penetration and high visitor registrations. This should ensure right crowd in right number at the show."
Various facilitation initiatives have been taken like recognizing preferred Airlines by negotiating rates between the ranges INR 499 to 999 from various sectors to Delhi, launching Key to business in India for international participants, doing a Travel Guide for all participants, online meeting scheduling facility for visitors, and so on!
JCK New Delhi 2008 is building to be a complete solution to all the buyer's needs from loose stones to a fine jewelry, from technology to packaging. The show promises to be a comprehensive showcase of ideas and concepts delivering an experience to its visitors!
Thursday, May 22, 2008
Wednesday, May 21, 2008
Why all the hoopla over that curious copper color?
And why is Oregon Sunstone Labradorite so very, very special?
It is my experience that you can tell how well a student understands the subject being taught based on the questions they ask. And given the questions that we are receiving about the Oregon Sunstone Labradorite issues, I can tell that there are a lot of people who really don’t understand exactly how all of this plays out regarding copper and the feldspars. So I thought that this week we would take a look at this curious copper color and why there is so much hoopla over the issues.
First, let’s take a look at the most simple type of copper coloration in a gemstone. At left you see native copper, the metal that U.S. pennies and water pipes world wide are made from. This is what it looks like coming out of the ground. But if you take a close look at the image (as well as the banner image at the top of the page) you will see some green color patches forming on our native copper. This is oxidation.
The mixing of the copper with oxygen causes the copper to expand and get all bubbly due to the oxidation as you can see in the image at right. When copper oxidizes it turns green and eventually bluish green in color, and forms what appears to be the bubble formations known as botryoidal formation that we see in malachite. And the image at right is indeed malachite, an oxidation of copper as we saw above that can be cut and polished into the beautiful gemstone that you see below.
But this is a very common gemstone formed by the actual copper itself. Much the same as azurite and turquoise are both combinations of copper and other elements forming into a single massive formation.
But what about the Oregon Sunstone Labradorite? What makes it so rare and different? Well, in the Oregon formations the copper is not a prime ingredient of the feldspar, but instead an inclusion. An impurity. So rather than the copper forming the gemstone, it is the cause of the color in the gemstone, and by virtually all of the textbooks it is effectively the only place on earth you can find copper as a coloring element in labradorite feldspar. And not only that, the result of the copper in the Oregon Labradorite formations produces gemstones that are unique in the world of gemology.
At left you see a slide show of increasing magnification where the copper grains inside the Oregon Sunstone Labradorite create the shiller effect, and as you increase the magnification you can actually see the minute grains of copper inside this Oregon Sunstone Labradorite.
But it gets better. In an exceptionally rare occurrence, the copper is extremely small in the feldspar and rather than occurring as a shiller effect in the stone as we saw at left, it actually imparts a remarkably beautiful solid red and/or green color to the labradorite. Why two colors? This is because copper has what is called multiple valences. Meaning that it can form more than one type of bond with other elements to form different types of molecules. Sort of like when you hold both hands with one person you form a group of two people. But when you hold one hand each with two other people, you form a group of three people. This is one of my now famous (or infamous to the science geeks) grass roots explanations to help you understand that just like you holding hands with one or two other people will create different types of groups, copper can do the same with other elements, which is how the Oregon Labradorite can offer the different colors due to different types of copper bonds. And I know that the techies will have fun with that one.
But in truth, this is very much how it works. And when it does it is not only beautiful, but quite rare and valuable. Below are photographs of the red and green rough, and a beautiful faceted Oregon Sunstone Labradorite from the Desert Sun Mining website.
So what we have is a very rare, very beautiful and very valuable gemstone that is native to Oregon in the United States . But there are many types of feldspar out there, and some gemstone dealers in places like Thailand and China know how to do some pretty creative stuff to make cheap gemstones look like expensive gemstone, and then pass them off for the real thing. So what if someone could take a cheaper and more plentiful form of feldspar such as an oligoclase (as seen below left), cook it up and infuse it with some form of copper to make it appear to be the far more rare and expensive Oregon Labradorite, even though it was not the Oregon material? (as seen below right).
It might look like the real Oregon Sunstone Labradorite. But it would actually be a much cheaper result of artificial color treatment of the stone, and would require that buyers be properly informed about the treatment to understand that they were not getting the real thing. But would the treaters do that? Or would they try to claim that they had found yet another very rare formation just like the Oregon Sunstone Labradorite, but in some far off place like the Congo , Mongolia , Tibet or other hard to reach spot. And if the Thailand or Chinese dealers did this, what might the story sound like, and how could we identify the treatment so we could separate it from the real Oregon Sunstone Labradorite? Maybe we could take a stone from the Congo and have a lapidary cut the ends off so we could transmit a light through it and see the infusion boundaries. Or perhaps run more Raman scans to get even better and more accurate results.
We are going to bring you the rest of this story next week. But for this first part I wanted to lay the foundation of this issue regarding the Oregon Sunstone Labradorite so you could understand the background to the issues. Next week we will finish the saga of this curious copper color in feldspar gemstones.
Robert James FGA, GG
President, International School of Gemology
It is my experience that you can tell how well a student understands the subject being taught based on the questions they ask. And given the questions that we are receiving about the Oregon Sunstone Labradorite issues, I can tell that there are a lot of people who really don’t understand exactly how all of this plays out regarding copper and the feldspars. So I thought that this week we would take a look at this curious copper color and why there is so much hoopla over the issues.
First, let’s take a look at the most simple type of copper coloration in a gemstone. At left you see native copper, the metal that U.S. pennies and water pipes world wide are made from. This is what it looks like coming out of the ground. But if you take a close look at the image (as well as the banner image at the top of the page) you will see some green color patches forming on our native copper. This is oxidation.
The mixing of the copper with oxygen causes the copper to expand and get all bubbly due to the oxidation as you can see in the image at right. When copper oxidizes it turns green and eventually bluish green in color, and forms what appears to be the bubble formations known as botryoidal formation that we see in malachite. And the image at right is indeed malachite, an oxidation of copper as we saw above that can be cut and polished into the beautiful gemstone that you see below.
But this is a very common gemstone formed by the actual copper itself. Much the same as azurite and turquoise are both combinations of copper and other elements forming into a single massive formation.
But what about the Oregon Sunstone Labradorite? What makes it so rare and different? Well, in the Oregon formations the copper is not a prime ingredient of the feldspar, but instead an inclusion. An impurity. So rather than the copper forming the gemstone, it is the cause of the color in the gemstone, and by virtually all of the textbooks it is effectively the only place on earth you can find copper as a coloring element in labradorite feldspar. And not only that, the result of the copper in the Oregon Labradorite formations produces gemstones that are unique in the world of gemology.
At left you see a slide show of increasing magnification where the copper grains inside the Oregon Sunstone Labradorite create the shiller effect, and as you increase the magnification you can actually see the minute grains of copper inside this Oregon Sunstone Labradorite.
But it gets better. In an exceptionally rare occurrence, the copper is extremely small in the feldspar and rather than occurring as a shiller effect in the stone as we saw at left, it actually imparts a remarkably beautiful solid red and/or green color to the labradorite. Why two colors? This is because copper has what is called multiple valences. Meaning that it can form more than one type of bond with other elements to form different types of molecules. Sort of like when you hold both hands with one person you form a group of two people. But when you hold one hand each with two other people, you form a group of three people. This is one of my now famous (or infamous to the science geeks) grass roots explanations to help you understand that just like you holding hands with one or two other people will create different types of groups, copper can do the same with other elements, which is how the Oregon Labradorite can offer the different colors due to different types of copper bonds. And I know that the techies will have fun with that one.
But in truth, this is very much how it works. And when it does it is not only beautiful, but quite rare and valuable. Below are photographs of the red and green rough, and a beautiful faceted Oregon Sunstone Labradorite from the Desert Sun Mining website.
So what we have is a very rare, very beautiful and very valuable gemstone that is native to Oregon in the United States . But there are many types of feldspar out there, and some gemstone dealers in places like Thailand and China know how to do some pretty creative stuff to make cheap gemstones look like expensive gemstone, and then pass them off for the real thing. So what if someone could take a cheaper and more plentiful form of feldspar such as an oligoclase (as seen below left), cook it up and infuse it with some form of copper to make it appear to be the far more rare and expensive Oregon Labradorite, even though it was not the Oregon material? (as seen below right).
It might look like the real Oregon Sunstone Labradorite. But it would actually be a much cheaper result of artificial color treatment of the stone, and would require that buyers be properly informed about the treatment to understand that they were not getting the real thing. But would the treaters do that? Or would they try to claim that they had found yet another very rare formation just like the Oregon Sunstone Labradorite, but in some far off place like the Congo , Mongolia , Tibet or other hard to reach spot. And if the Thailand or Chinese dealers did this, what might the story sound like, and how could we identify the treatment so we could separate it from the real Oregon Sunstone Labradorite? Maybe we could take a stone from the Congo and have a lapidary cut the ends off so we could transmit a light through it and see the infusion boundaries. Or perhaps run more Raman scans to get even better and more accurate results.
We are going to bring you the rest of this story next week. But for this first part I wanted to lay the foundation of this issue regarding the Oregon Sunstone Labradorite so you could understand the background to the issues. Next week we will finish the saga of this curious copper color in feldspar gemstones.
Robert James FGA, GG
President, International School of Gemology
Saturday, May 17, 2008
Introduction to Diamonds
The mined stones are classified into different varieties
1. Diamonds, well crystallized, transparent and gem quality
2. Bort, boart or bortz, poorly crystallized, grey to brown in color, translucent to opaque and used mostly in industry as an abrasive. The large and black stones of granular crystalline structure found almost exclusively in the state of Bahia in Brazil are also known as carbonado or carbonate.
3. Ballas – spherical masses of minute diamond crystals more or less concentrically arranged. The mass in very hard and rough and has important industrial applications.
Rough diamond crystals are mostly of diameter lass than a millimeter in diameter. Bog crystals are extremely rare and so valuable that they acquire the status of an antique and are known by special and distinctive names. History and legend play a bigger part than the actual inherent value of these stones. They are mostly found as part of the crown jewels of various nations.
A natural diamond mines from the earth always has inclusions of graphatite or other minerals that are visible as dark sports in the rough stone. Voids often filled with as are visible as white or shiny spots within the stone. Stones that do not have any inclusions even under 50x magnification are extremely rare and are collectors items.
Carbons atoms arranged in inter-penetrating face-centered cubic lattices form the crystal structure of diamonds. An infinitely large crystal would be totally colorless and transparent except to ultraviolet light of wavelengths shorter than 230nm. However, all natural diamonds contain defects in the crystal lattice as well as impurity elements and these defects cause color in the stone. Again, the growth patterns may abruptly change, with further layers becoming mirror images of the earlier growth. The twining that often occurs within the crystal makes the crystals very hard to cut and they are called macles.
Diamonds have been found all over the world, the most ancient and famous being old Indian deposits that were worked from earliest times. Till about the late 1700s, all the diamonds in the world were found in fields and on river beds, mostly near Hyrdabad in the Deccan plateau. Large stones like the Kohinoor were found there around 1300AD. The town of Golconda so became the center of the diamond trade of the world. In spite of the output from India, Borneo, and to some extent Brazil, diamonds were very rare. Valuable diamond fields in the gold mining area of Minas Geraiswere discovered in Brazil about 1725. Portuguese merchants took Brazillian diamonds to Goa, India, to pass them off as Indian stones. Mining was carried out so intensively in Brazil that the main areas were almost exhausted within twenty years.
At about the time that the Brazilian fields were being depleted, the first diamond field of South Africa was discovered in 1886Ad, when children of a Boer farmer found “a pretty pebble” in the dandy bed of the Vaal River. Four years later, diamonds were found in the earth far from a river source, and the practice of dry-digging for diamonds was born. More sophisticated mining techniques allowed deeper subterranean digging, as well as more efficient river marine mining than ever before. By 1871 world annual production, mostly from South Africa, exceeded a million carats. Soon South Africa had the monopoly for diamond production, until major deposits ere found in Siberian permafrost in 1954. Currently Western Canada is the site of the world’s newest diamond rush. Diamonds have also been found in Urals and in Australia and these sources compete with South Africa.
Diamonds are extensively used in industry, but are better known for their use as gemstones. The value of a diamond depends in size, quality and shape. In the seventeenth century, Tavernier recorded that the value of a diamond was proportional to the squire of the weight, and this is still true. The most popular cut as a gemstone is the brilliant, a round cut with 58 facets that was developed to obtain the maximum brilliance and fire from the stone. There are also other fancy cuts like the kite, triangle, and baguette. The term melee refers to stones cut from small fragments of larger rough stones, obtained after cutting. Approximately 8-16 such stones together weight one carat, and many of these small stones are cut with 58 facets. Similar melee stones are cut with only 18 facets and maybe as small as 0.01 carat each.
Merchants found that the dried brown fruit of the locust tree, which looked like a horn, had seeds of an extraordinary uniform weight. In course of time, the seed, the keration or carat became the standard for weighing diamonds and gold. Now the standard weight for diamonds is the carat (200mg), rather than the more picturesque seed.
When heated in oxygen above 650C, a coating of graphite forms on the diamond. In an inert atmosphere, the transition to graphite occurs above 1570C. Diamond is extremely inert to acids and chemicals until heated to 1020K, but sodium nitrate attacks it at 430C and metals react to form carbides. At pressures of 70,000 atmospheres and 2500C, graphite may crystallize into diamond. The specific gravity of diamond is 3.5 and its refractive index is 2.4 as against 1.5 for glass and 1.33 for water. Diamond also has high dispersion and this gives fire to the crystal. Diamond conducts heat but is a good electrical insulator; this is a sure way to detect a real stone from fakes.
Almost all diamonds contain impurity atoms, mainly nitrogen and boron, but these cannot be seen even at the highest magnification. The effect of these impurities is to change the properties of the stone, mostly by giving it a light color. For instance, the nitrogen tends to collect into small clusters of two to three atoms and the interactions between the carbon and nitrogen atoms create new energy levels in the crystal. An optical center is formed that absorbs light of wavelengths longer than 230nm. Natural diamonds may have several such optical centers of different configurations. When a single nitrogen atom substitutes for a carbon atom, an N3 optical center is formed and the ultraviolet absorption edge comes close to the visible region. The “A” optical center produced when nitrogen atoms replace 2 adjacent carbon atoms gives substantial infrared absorption in the region 10,000 to 7000nm. An arrangement of 4 nitrogen atoms around a missing carbon atom gives a B center with the result that the ultraviolet absorption is lowered through the infrared spectra of A and B centers as similar. The addiction of a nearby vacancy in the carbon lattice results in the so-called H3 and H4 centers.
Natural diamonds contain these optical centers in randomly variable concentration and gemologists label the type of diamond according to the absorption spectrum. Most diamonds have N3, A and B centers and these are the Type I sort. Type Ia diamonds contain primarily A and B centers, but if N3 centers are predominant, it becomes Type Ib. the Type Ia is further divided into Type IaA and Type IaB according to whether there are greater A or B centers. Type II diamonds have little or no nitrogen in them but may contain boron that makes them electrically conducting; these are the somewhat rare type IIb semi-conducting stones. In nature, it is possible to find stones which are of more than one type. Synthetic diamonds are usually Type Ib and may have up to ten percent of iron and nickel as contamination from the process. Ultraviolet, X-rays and electrons excite luminescence in diamond that is usually blue though often yellow and green colors are seen.
In general though, the color of diamond is not directly related to the impurities and their concentrations but us due to defects produced in the lattice by the impurity atoms. Bombardment of the crystal by atomic particles can knock out carbon atoms from their positions in the crystal lattice, produce defects and so induce color. Gamma rays and X-rays do not have any mass and so cannot displace the carbon atoms and thus do not produce defects.
Exposed to a stream of high energy electrons, the diamonds attain a blue shade, the depth depending on the penetration of the electron into the stone. Electron-hole pairs are trapped at the defects that absorb red light and so color the stone blue, but this color fades with gentle heating. A high energy electron colliding with a carbon atom could give it enough energy for it to knock other carbon atoms out of their places. For example electrons of 13 MeV from a big accelerator can give a carbon atom a maximum energy of 35 KeV; this atom is capable of displacing about a hundred other atoms. This cascade of collisions tends to make the diamond greenish in color. Neutrons and alpha particles are far more effective in transferring energy to the carbon atoms and the cascade of collisions turn the diamonds into a definite green color. Even the diamond only a small distance and the color is a surface effect that may disappear when the stone is polished.
1. Diamonds, well crystallized, transparent and gem quality
2. Bort, boart or bortz, poorly crystallized, grey to brown in color, translucent to opaque and used mostly in industry as an abrasive. The large and black stones of granular crystalline structure found almost exclusively in the state of Bahia in Brazil are also known as carbonado or carbonate.
3. Ballas – spherical masses of minute diamond crystals more or less concentrically arranged. The mass in very hard and rough and has important industrial applications.
Rough diamond crystals are mostly of diameter lass than a millimeter in diameter. Bog crystals are extremely rare and so valuable that they acquire the status of an antique and are known by special and distinctive names. History and legend play a bigger part than the actual inherent value of these stones. They are mostly found as part of the crown jewels of various nations.
A natural diamond mines from the earth always has inclusions of graphatite or other minerals that are visible as dark sports in the rough stone. Voids often filled with as are visible as white or shiny spots within the stone. Stones that do not have any inclusions even under 50x magnification are extremely rare and are collectors items.
Carbons atoms arranged in inter-penetrating face-centered cubic lattices form the crystal structure of diamonds. An infinitely large crystal would be totally colorless and transparent except to ultraviolet light of wavelengths shorter than 230nm. However, all natural diamonds contain defects in the crystal lattice as well as impurity elements and these defects cause color in the stone. Again, the growth patterns may abruptly change, with further layers becoming mirror images of the earlier growth. The twining that often occurs within the crystal makes the crystals very hard to cut and they are called macles.
Diamonds have been found all over the world, the most ancient and famous being old Indian deposits that were worked from earliest times. Till about the late 1700s, all the diamonds in the world were found in fields and on river beds, mostly near Hyrdabad in the Deccan plateau. Large stones like the Kohinoor were found there around 1300AD. The town of Golconda so became the center of the diamond trade of the world. In spite of the output from India, Borneo, and to some extent Brazil, diamonds were very rare. Valuable diamond fields in the gold mining area of Minas Geraiswere discovered in Brazil about 1725. Portuguese merchants took Brazillian diamonds to Goa, India, to pass them off as Indian stones. Mining was carried out so intensively in Brazil that the main areas were almost exhausted within twenty years.
At about the time that the Brazilian fields were being depleted, the first diamond field of South Africa was discovered in 1886Ad, when children of a Boer farmer found “a pretty pebble” in the dandy bed of the Vaal River. Four years later, diamonds were found in the earth far from a river source, and the practice of dry-digging for diamonds was born. More sophisticated mining techniques allowed deeper subterranean digging, as well as more efficient river marine mining than ever before. By 1871 world annual production, mostly from South Africa, exceeded a million carats. Soon South Africa had the monopoly for diamond production, until major deposits ere found in Siberian permafrost in 1954. Currently Western Canada is the site of the world’s newest diamond rush. Diamonds have also been found in Urals and in Australia and these sources compete with South Africa.
Diamonds are extensively used in industry, but are better known for their use as gemstones. The value of a diamond depends in size, quality and shape. In the seventeenth century, Tavernier recorded that the value of a diamond was proportional to the squire of the weight, and this is still true. The most popular cut as a gemstone is the brilliant, a round cut with 58 facets that was developed to obtain the maximum brilliance and fire from the stone. There are also other fancy cuts like the kite, triangle, and baguette. The term melee refers to stones cut from small fragments of larger rough stones, obtained after cutting. Approximately 8-16 such stones together weight one carat, and many of these small stones are cut with 58 facets. Similar melee stones are cut with only 18 facets and maybe as small as 0.01 carat each.
Merchants found that the dried brown fruit of the locust tree, which looked like a horn, had seeds of an extraordinary uniform weight. In course of time, the seed, the keration or carat became the standard for weighing diamonds and gold. Now the standard weight for diamonds is the carat (200mg), rather than the more picturesque seed.
When heated in oxygen above 650C, a coating of graphite forms on the diamond. In an inert atmosphere, the transition to graphite occurs above 1570C. Diamond is extremely inert to acids and chemicals until heated to 1020K, but sodium nitrate attacks it at 430C and metals react to form carbides. At pressures of 70,000 atmospheres and 2500C, graphite may crystallize into diamond. The specific gravity of diamond is 3.5 and its refractive index is 2.4 as against 1.5 for glass and 1.33 for water. Diamond also has high dispersion and this gives fire to the crystal. Diamond conducts heat but is a good electrical insulator; this is a sure way to detect a real stone from fakes.
Almost all diamonds contain impurity atoms, mainly nitrogen and boron, but these cannot be seen even at the highest magnification. The effect of these impurities is to change the properties of the stone, mostly by giving it a light color. For instance, the nitrogen tends to collect into small clusters of two to three atoms and the interactions between the carbon and nitrogen atoms create new energy levels in the crystal. An optical center is formed that absorbs light of wavelengths longer than 230nm. Natural diamonds may have several such optical centers of different configurations. When a single nitrogen atom substitutes for a carbon atom, an N3 optical center is formed and the ultraviolet absorption edge comes close to the visible region. The “A” optical center produced when nitrogen atoms replace 2 adjacent carbon atoms gives substantial infrared absorption in the region 10,000 to 7000nm. An arrangement of 4 nitrogen atoms around a missing carbon atom gives a B center with the result that the ultraviolet absorption is lowered through the infrared spectra of A and B centers as similar. The addiction of a nearby vacancy in the carbon lattice results in the so-called H3 and H4 centers.
Natural diamonds contain these optical centers in randomly variable concentration and gemologists label the type of diamond according to the absorption spectrum. Most diamonds have N3, A and B centers and these are the Type I sort. Type Ia diamonds contain primarily A and B centers, but if N3 centers are predominant, it becomes Type Ib. the Type Ia is further divided into Type IaA and Type IaB according to whether there are greater A or B centers. Type II diamonds have little or no nitrogen in them but may contain boron that makes them electrically conducting; these are the somewhat rare type IIb semi-conducting stones. In nature, it is possible to find stones which are of more than one type. Synthetic diamonds are usually Type Ib and may have up to ten percent of iron and nickel as contamination from the process. Ultraviolet, X-rays and electrons excite luminescence in diamond that is usually blue though often yellow and green colors are seen.
In general though, the color of diamond is not directly related to the impurities and their concentrations but us due to defects produced in the lattice by the impurity atoms. Bombardment of the crystal by atomic particles can knock out carbon atoms from their positions in the crystal lattice, produce defects and so induce color. Gamma rays and X-rays do not have any mass and so cannot displace the carbon atoms and thus do not produce defects.
Exposed to a stream of high energy electrons, the diamonds attain a blue shade, the depth depending on the penetration of the electron into the stone. Electron-hole pairs are trapped at the defects that absorb red light and so color the stone blue, but this color fades with gentle heating. A high energy electron colliding with a carbon atom could give it enough energy for it to knock other carbon atoms out of their places. For example electrons of 13 MeV from a big accelerator can give a carbon atom a maximum energy of 35 KeV; this atom is capable of displacing about a hundred other atoms. This cascade of collisions tends to make the diamond greenish in color. Neutrons and alpha particles are far more effective in transferring energy to the carbon atoms and the cascade of collisions turn the diamonds into a definite green color. Even the diamond only a small distance and the color is a surface effect that may disappear when the stone is polished.
Friday, May 16, 2008
Diamonds in India - Part II
Kurnool District: A conglomerate bed about ten meters thick is found here. Diamonds occurred and still appear in the layers of this bed as small blue, green or yellow grains. The old kingdoms of Bijapur and Golconda had 38 diamond mines close to the Krishna river and other mines have also been reported by travelers. In general the mines were located in alluvium or river gravel, sedimentary rocks or archean crystalline rocks. The other areas where stones were found after rain were near the Banganapalle conglomerates. The layers were mines by sinking shafts of about 3-5 meters depth with galleries going along the seam. However, these diamonds were of poor quality being colored small and highly flowed.
Mines at Komarulu and Dhone have produced diamonds of medium quality but on the other hand the Lanjapolur stones were of a better grade. However the mines generated no revenue since 1813. These mines at Ramallakota and Varakaru produced stones of excellent quality, though of very small size. According to Tavernier, these stones were extracted from sand or the surrounding earth that occupied narrow veins in the rock. Near Virayapalle the diamonds yield was incredibly large, one carat of flawless and well formed gemstones from seven tones of ore. But since 1910 there has apparently been no output or even mining operations in this area.
Guntur District: the largest mining operations were at Kollur and the location of this mine was referred to by Tavernier as “color” and sometimes as Quolore. In 1645 it employed nearly sixty-thousand persons in very productive mining operations. Three decade later, the tract appeared to have been exhausted and it is now deserted. Legend has it that the Kohinoor or the great Mogul was found here.
Krishna District: The mines at Partiala, north-west of Vijayawada, yielded mainly yellowish or reddish colored diamonds in gravel some ten meters below the surface. The description by Scott Tallies with the procedures described by Tavernier at Kollur except for the curious fact that at Partiala, women were not allowed near the mines. Contemporary accounts state that the famous pit diamond came from one of these mines. The Kodavatakallu mines between the Muniair and the Krishna rivers produced several bullock cart loads of diamonds according to local lore.
Bengal: The Ain-i-Akbari refers to a diamond mines near Hirpah in Burdwasdistrict but this is now discounted for lack of confirmation.
Bihar: The ancient work, Tuzuk-i-Jahangiri mentions a diamond field near the source of the Sunk river, south of the watershed of the Koel river in Ranchi district. However, no stones of any value have been found here in recent times. Tavernier refers to the Soumelapur mines close to the village of Simh in Palamau district, where the sands of the Koel river were prospected for diamonds and where large stones were occasionally found.
Madhya Pradesh: Abdul Fazal mentions the mines at Wairagarh. By 1827 these very productive mines were exhausted and by 1843 the abandoned workings were barely visible. Lying between the Panna shale and the upper kaimur sandstone, the diamond containing layer in Panna district is a conglomerate of about 2m thickness. Diamonds occur in the joints and bedding plains of the kaimur sandstones rocks or in the alluvial cover. North-East of Itwa the bed is localized, where reports have it that diamonds are found in the Majhgawan area occur in a volcanic neck filled with agglomerate tuff. The soft and very friable volcanic rock in which diamonds occur is yellow to yellowish green and is a 100km long and about 20km wide. This volcanic pipe is opined to be the main source of diamonds and other such volcanic pipes are thought to exist in the area. Mining in the Panna fields is done by agriculturists between February and June, with claims of 10sqm each. The prospects for diamond mining were reported to be good in 1954, but nothing further was done. The Panna mines are now the only visible Indian source of diamonds for industrial and gem varieties. The production was about 5% lower in 1971 than in the previous year. The total reserves of diamonds are estimated to be 410000 carats in these regions.
Baraunda: Diamonds were once plentiful in this area on the north bank of the Chahala river, but mining ceased after a find of 12-24 stones of which one weight about 118 carats.
Orissa: The gravel bed of the Ib, a tributary of the Mahanadi river a few miles from Sambalpur as well as other tributaries of the Mahanadi as far up as the Mand river have been dredged successfully for diamonds. Between 1804 and 1818 twenty stones were found of which the largest rough found in 1809, weighed 218 carats. The sands from the streams near Bpndesor in Kalahandi have yielded minute diamonds, but a systematic search for larger stones had not been made.
Since 1926, the Panna diamond mining syndicate, the Mahalakshmi diamond mine works and Charkari mining works were the main companies involved in diamond mining. No serious and systematic surveys were made by these companies to look for diamonds. In 1954 Russian assistance was sought for a plan for modernization that would cost 6 million rupees and handle six thousand to seven thousand tones of ore a day, but this effort seems to have failed. At present, any diamonds that may be found must be handed over to the government of India. The diamond officer in Panna records the weight and characteristics of the stones before they are auctioned. The person who found the stones then gets a reward of one quarter of the sale price. Panna production is presently very small in comparison with world output, but the diamonds are on the average priced higher than those from South Africa.
Mines at Komarulu and Dhone have produced diamonds of medium quality but on the other hand the Lanjapolur stones were of a better grade. However the mines generated no revenue since 1813. These mines at Ramallakota and Varakaru produced stones of excellent quality, though of very small size. According to Tavernier, these stones were extracted from sand or the surrounding earth that occupied narrow veins in the rock. Near Virayapalle the diamonds yield was incredibly large, one carat of flawless and well formed gemstones from seven tones of ore. But since 1910 there has apparently been no output or even mining operations in this area.
Guntur District: the largest mining operations were at Kollur and the location of this mine was referred to by Tavernier as “color” and sometimes as Quolore. In 1645 it employed nearly sixty-thousand persons in very productive mining operations. Three decade later, the tract appeared to have been exhausted and it is now deserted. Legend has it that the Kohinoor or the great Mogul was found here.
Krishna District: The mines at Partiala, north-west of Vijayawada, yielded mainly yellowish or reddish colored diamonds in gravel some ten meters below the surface. The description by Scott Tallies with the procedures described by Tavernier at Kollur except for the curious fact that at Partiala, women were not allowed near the mines. Contemporary accounts state that the famous pit diamond came from one of these mines. The Kodavatakallu mines between the Muniair and the Krishna rivers produced several bullock cart loads of diamonds according to local lore.
Bengal: The Ain-i-Akbari refers to a diamond mines near Hirpah in Burdwasdistrict but this is now discounted for lack of confirmation.
Bihar: The ancient work, Tuzuk-i-Jahangiri mentions a diamond field near the source of the Sunk river, south of the watershed of the Koel river in Ranchi district. However, no stones of any value have been found here in recent times. Tavernier refers to the Soumelapur mines close to the village of Simh in Palamau district, where the sands of the Koel river were prospected for diamonds and where large stones were occasionally found.
Madhya Pradesh: Abdul Fazal mentions the mines at Wairagarh. By 1827 these very productive mines were exhausted and by 1843 the abandoned workings were barely visible. Lying between the Panna shale and the upper kaimur sandstone, the diamond containing layer in Panna district is a conglomerate of about 2m thickness. Diamonds occur in the joints and bedding plains of the kaimur sandstones rocks or in the alluvial cover. North-East of Itwa the bed is localized, where reports have it that diamonds are found in the Majhgawan area occur in a volcanic neck filled with agglomerate tuff. The soft and very friable volcanic rock in which diamonds occur is yellow to yellowish green and is a 100km long and about 20km wide. This volcanic pipe is opined to be the main source of diamonds and other such volcanic pipes are thought to exist in the area. Mining in the Panna fields is done by agriculturists between February and June, with claims of 10sqm each. The prospects for diamond mining were reported to be good in 1954, but nothing further was done. The Panna mines are now the only visible Indian source of diamonds for industrial and gem varieties. The production was about 5% lower in 1971 than in the previous year. The total reserves of diamonds are estimated to be 410000 carats in these regions.
Baraunda: Diamonds were once plentiful in this area on the north bank of the Chahala river, but mining ceased after a find of 12-24 stones of which one weight about 118 carats.
Orissa: The gravel bed of the Ib, a tributary of the Mahanadi river a few miles from Sambalpur as well as other tributaries of the Mahanadi as far up as the Mand river have been dredged successfully for diamonds. Between 1804 and 1818 twenty stones were found of which the largest rough found in 1809, weighed 218 carats. The sands from the streams near Bpndesor in Kalahandi have yielded minute diamonds, but a systematic search for larger stones had not been made.
Since 1926, the Panna diamond mining syndicate, the Mahalakshmi diamond mine works and Charkari mining works were the main companies involved in diamond mining. No serious and systematic surveys were made by these companies to look for diamonds. In 1954 Russian assistance was sought for a plan for modernization that would cost 6 million rupees and handle six thousand to seven thousand tones of ore a day, but this effort seems to have failed. At present, any diamonds that may be found must be handed over to the government of India. The diamond officer in Panna records the weight and characteristics of the stones before they are auctioned. The person who found the stones then gets a reward of one quarter of the sale price. Panna production is presently very small in comparison with world output, but the diamonds are on the average priced higher than those from South Africa.
Another very beautiful jewelry website "Orna & Rinat"
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Diamond Tools
This is a email I got from one of my friend. I hope this will be important for you also. Here is that email as it is...!
Very glad to know your company at the exhibition ! Our factory, Shaboss Abrasive Tools Co., Ltd. has 15years experience of produces exporting the diamond tools , abrasive tools Pliers and Nail Files ,The websites that please enter our factory look over Http://www.diamondtools.com.cn Http://www.plierstool.com Our factory and a lot of famous companies in the world are in the cooperative products,Has your company needed to purchase products recently? Please give me a type and photo, I will help you to purchase , We wish would consider to accept us as your OEM supplier, Waiting for your comments and wish we have a good cooperation!
Best regards and thanks!
Cinky Lu
Shaboss Abrasive Tools Co., Ltd.
Shanghai Ruijiang Machinery & Equipment Import & Export Co., Ltd.
Add:C1,8/F.,Jiangsu Mansion,528 East Laoshan Rd.,Shanghai China
Tel:+86-21-68868420 58760223 Fax:+86-21-68868425 58760223
Mobile:0086-13817743222 P.C:200122
Http://www.diamondtools.com.cn Http://www.plierstool.com
E--Mail: lxdtools@hotmail.com
Very glad to know your company at the exhibition ! Our factory, Shaboss Abrasive Tools Co., Ltd. has 15years experience of produces exporting the diamond tools , abrasive tools Pliers and Nail Files ,The websites that please enter our factory look over Http://www.diamondtools.com.cn Http://www.plierstool.com Our factory and a lot of famous companies in the world are in the cooperative products,Has your company needed to purchase products recently? Please give me a type and photo, I will help you to purchase , We wish would consider to accept us as your OEM supplier, Waiting for your comments and wish we have a good cooperation!
Best regards and thanks!
Cinky Lu
Shaboss Abrasive Tools Co., Ltd.
Shanghai Ruijiang Machinery & Equipment Import & Export Co., Ltd.
Add:C1,8/F.,Jiangsu Mansion,528 East Laoshan Rd.,Shanghai China
Tel:+86-21-68868420 58760223 Fax:+86-21-68868425 58760223
Mobile:0086-13817743222 P.C:200122
Http://www.diamondtools.com.cn Http://www.plierstool.com
E--Mail: lxdtools@hotmail.com
25th MidEast Watch & Jewellery Show (October 8-12, 2008)
The 25th edition of MidEast Watch & Jewellery Show is set to be held at Expo Centre Sharjah from 8th to 12th October 2008. We are pleased to invite you to participate at the event. The show, a favourite among the leading jewellers in the industry for launching new designs is considered to be the most successful watch and jewellery event in the region.
UAE is one of the top gold-consuming countries in the world and also a major hub of the physical gold trade in the Middle East and Asia. Diamond sale is also on the upswing with the Gulf being the fourth largest market in the world. Industry sources say demand for diamond jewellery has been increasing by more than 40% for the past two years. Rough diamond trade in Dubai itself totaled to US$ 4.8 billion in 2007. In 2007, gold demand rose eight percent to 99.8 tonnes in the UAE according to the World Gold Council figures.
Visitors, both trade and direct buyers, from across the Middle East flock to every edition of the show in search of the most fascinating and wide ranging choices in gold, diamond, pearl, silver, gems, precious stones, loose pearls, watches and other jewellery displays. The strong and extensive visitor campaigns carried out well in advance ensures the turnout of substantial and quality visitors. The MidEast Watch & Jewellery Show is aimed at attracting jewellery trade buyers, importers, traders and retailers and private collectors from across the Middle East region. The event has set an achievement in high sales figures by record gold sales in the country last year.
The show has over the decades gained reputation and acclaim as the Middle East’s longest running watch & jewellery event. It is therefore not surprising that the event boasts of an exhibitor retention rate of over 90%, one of the highest in the region.
The last show in April this year featured more than 350 exhibitors from 25 countries with a 30 per cent increase in exhibition space sold and number of exhibitors over the previous edition. It attracted a record 46,908 trade and direct buyers.
To be a part of this successful show, just complete the enclosed reply form and return to us immediately. On receipt of the form, we will get in touch with you with all the necessary information.
Please visit our website: www.mideastjewellery.com for more information about the show.
Thank you and we look forward to your response.
Sincerely yours,
Abid Maqsood
Cell: +971 50 4742249
Dir: +971 6 5991 201
Main: +971 6 5770 000
Fax: +971 6 5770 111
Email: abid@expo-centre.ae
Web: www.expo-centre.ae
UAE is one of the top gold-consuming countries in the world and also a major hub of the physical gold trade in the Middle East and Asia. Diamond sale is also on the upswing with the Gulf being the fourth largest market in the world. Industry sources say demand for diamond jewellery has been increasing by more than 40% for the past two years. Rough diamond trade in Dubai itself totaled to US$ 4.8 billion in 2007. In 2007, gold demand rose eight percent to 99.8 tonnes in the UAE according to the World Gold Council figures.
Visitors, both trade and direct buyers, from across the Middle East flock to every edition of the show in search of the most fascinating and wide ranging choices in gold, diamond, pearl, silver, gems, precious stones, loose pearls, watches and other jewellery displays. The strong and extensive visitor campaigns carried out well in advance ensures the turnout of substantial and quality visitors. The MidEast Watch & Jewellery Show is aimed at attracting jewellery trade buyers, importers, traders and retailers and private collectors from across the Middle East region. The event has set an achievement in high sales figures by record gold sales in the country last year.
The show has over the decades gained reputation and acclaim as the Middle East’s longest running watch & jewellery event. It is therefore not surprising that the event boasts of an exhibitor retention rate of over 90%, one of the highest in the region.
The last show in April this year featured more than 350 exhibitors from 25 countries with a 30 per cent increase in exhibition space sold and number of exhibitors over the previous edition. It attracted a record 46,908 trade and direct buyers.
To be a part of this successful show, just complete the enclosed reply form and return to us immediately. On receipt of the form, we will get in touch with you with all the necessary information.
Please visit our website: www.mideastjewellery.com for more information about the show.
Thank you and we look forward to your response.
Sincerely yours,
Abid Maqsood
Cell: +971 50 4742249
Dir: +971 6 5991 201
Main: +971 6 5770 000
Fax: +971 6 5770 111
Email: abid@expo-centre.ae
Web: www.expo-centre.ae
Tuesday, May 13, 2008
Diamonds in India - Part I
Diamonds were found only in India before the discovery of the Brazilian deposits. The mining operations in Madhya Pradesh and Andhra Pradesh dateback to the sixth century AD. The mines of Vindhya Pradesh now in the state of Madhya Pradesh, were said to have produced diamonds worth ten thousand dollars during the reign of Akbar the great. The kings of Golconda and Vijayanagar leased out the shallow mines in the seventeenth century on a royalty system and on condition that rough stones weighting over 25 carats be surrendered to the kings for their personal adornments. In 1662AD,
Mthold, Andreas Sorcery and Adolph Thomson reported that the king received $120000 from the mine operators and stones larger than 10 carats were given to the king. According to Tavernier, between 1632 and 1662 AD, Ramallakota and Kollur were the mining centers, the latter being the most productive in 1645. The quality of the stones was so good and the size so large that the east India Company even considered sending remittances to England in the form of diamonds. The Golapalli and Malavalli mines were most productive in the sixteenth and seventeenth centuries but by the nineteenth century production had declined. Though mining operations in Panna in Madhya Pradesh was interrupted for some time, in continues to this day.
Mthold, Andreas Sorcery and Adolph Thomson reported that the king received $120000 from the mine operators and stones larger than 10 carats were given to the king. According to Tavernier, between 1632 and 1662 AD, Ramallakota and Kollur were the mining centers, the latter being the most productive in 1645. The quality of the stones was so good and the size so large that the east India Company even considered sending remittances to England in the form of diamonds. The Golapalli and Malavalli mines were most productive in the sixteenth and seventeenth centuries but by the nineteenth century production had declined. Though mining operations in Panna in Madhya Pradesh was interrupted for some time, in continues to this day.
The Wairagarh mines of Madhya Pradesh become uneconomical in 1829 and were abandoned in 1840 AD. In the seventeenth century, some diamonds were extracted in Bihar and Orissa, though production increased in the eighteenth century; but by the middle of the nineteenth century there was a decline in mining activity here too. In these regions the mining operations were primitive and consisted mainly of sporadic searches in shallow excavations.
The excavated material was soaked in water for a couple of days, sun dried and powdered in wooden pestles and mortars. The resultant grit was then scanned for gemstones.
Geologists have observed pipe rocks in Wajrakarur, once a flourishing mining area fourteen kilometers south of Guntakal as well as in Panna in Madhya
Pradesh, but they have not located the actual neck of the pipe. Close studies of the geological formations of central India indicate clearly the presence of diamonds in three distinct regions of India. The first is close to the rocks of the Kurnool series in Andhra Pradesh and the Vindhyas in the north. In Ananthapur, Bellary, Cuddapah, Kurnool, Krishna and Godavari districs of Andhra Pradesh, the rocks have weathered and farmers have chanced on diamonds when plugging their fields. The source of these alluvial stones has yet not been traced. The second source of alluvial diamonds extends westwards from the Mahanadi valley in the Sambalpur district of Orissa into Madhya Pradesh, with an extension to the north. Diamonds have
also been discovered in an outcrop of conglomerate that extends over an area of one hundred kilometers by 20km in Panna, Charkari, Bijwar, Ajaigarh, Kothi, Pathar Kacchar, Baraunda and Chobapur.
Geologists have reported that diamonds have been found in various locations in India listed below.
Ananthapur District: Diamonds have been extracted from the crystalline rocks near Bodasanipalle, Ganjikuta, Konganapalle, Lattawaram, Mulakalapenta, Pedda Hoturu and in Wajrakarur in the past. About a century ago, a volcanic neck very similar to the diamond bearing matrix of Kimberley in South Africa was discovered. Miners of that time crushed the ore and washed it on small platforms. In 1885, a small mining company tried unsuccessfully to mine the area but it was only in 1941 that the new Wajrakarur Diamond Company Ltd
found two large stones of around 1.8 carats each. Even today diamonds are occasionally found on the surface east of Wajrakarur after a rain storm, though never close to the neck of the pipe rock. Valuable stones are still found occasionally between Guntakal and Gooty in the village of Kanganapalle. In 1935, a cultivator reportedly picked up a diamond weighing about 36 carats and a few months earlier, a diamond weighing 67.4 carats was found and cut to an exceptionally brilliant stone of 24.6 carats.
Bellary District: While there was evidence of lining near the village of Huvinahadagalli, there are no record of actual finds if large stones.
Cuddapah District: There were attempts to mine the alluvium near hennur. It is reputed that large stones were found there but systematic and organized mining proved unprofitable. The stones were obtained from a gravel bed lying about two meters below the surface but the mines were soon abandoned.
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