The price per gram of a diamond increases with its weight but stones beyond a certain size are so rare that they cannot be valued on this scale. The few very large and spectacular diamonds are priceless and can trace their complex and controversial history through tales of war, intrigue and love. It is, in fact, the story of their passage through the lives of several owners and not their size, lustre or other properties that determines the price that they command.
The Kohinoor or the 'Mountain of Light' diamond was found two thousand five hundred years ago by a villager of Matanga in Kollur in Andra Pradesh, India. Old palm leaf manuscripts record the weight of the rough stone as 1986 carats. Sanskrit legends report that the Karna, the king of Anga, wore this diamond in his crown to give him invincibility during the great Mahabharata war. The stone later came into the possession of Emperor Vikramaditya of Ujjain (60BC). During the early Persian invasion of India, the diamond was apparently taken to the court of Darius the Great but after the break up of the Persian Empire, the gem found its way back to India. There is recorded evidence that the Kohinoor was with the family of the Rajah of Malwa in India. For several centuries, having been passed down from generation to generation. When the Moghul invated the India, Sultan Babar, the first of the Moghul emperors, acquired the diamond in 1340AD. It was hidden in the treasury for about two centuries and in 1526 the diamond was set as one of the peacock's eyes in the famous Peacock Throne of Shah Jahan.
In 1979, Nadir Shah of Persia, invated India and captured Delhi and seized the Peacock Throne but could not find the Kohinoor diamond. He later learn from that the Moghul emperor had hidden the stone in his turban. Historians disagree about the source of the name of the stone and insist that the name was variant on Kollur, where it was found.
Thursday, July 23, 2009
Gemstones Enhancement in Sri Lanka
The trade of gemstones is phenomenally large, the annual turnover being more than US$50 billion. A major share of this market is in diamonds, as these stones are bought for investment as well as for decorative purposes. The price of a diamond, however, has no relation to the actual cost of production, but lies in its comparative rarity. Over the years, by controlling the quantity of diamonds entering the market, the diamond trading company has kept the price of good quality diamonds stable and at a high level, ensuring its investment value. Sales publicity by jewellers, too, has encouraged a preference for diamonds over that for other gems. Substitutes like cubic zirconia, moissanite and Yttrium Aluminium Garnet (YAG), though equally lustrous and attractive, do not have the same appeal.
Most gemstones, diamonds included, are pale in color, often with inclusions, cracks or voids and since such stones are commonly available, they are cheap and so difficult to sell to discerning buyers. The improvement of the color and the clarity of these low quality stones is therefore of extreme importance to the trade. Research in material science has now given us the ways to improve the appearance of gemstones permanently and there is indeed considerable enhancement in the value of gemstones after treatment. On the other hand, there are people who have voiced serious objections to altering what nature has provided. It is a fact though that man is constantly improving on nature to make profits for himself, whether it is plastic surgery or gemstone enhancement.
There are many techniques used to enhance the color and quality of gemstones. Radiation treatment using gamma rays, electrons, x-rays are few. The most famous method of gemstone treatment is heat treatment. Specially corundums are heat treated to produce bright color blue sapphires. Heat treatment is a very popular method for enhancing colors of sapphires. Heat treatment to standards are accepted by the trade.
Most gemstones, diamonds included, are pale in color, often with inclusions, cracks or voids and since such stones are commonly available, they are cheap and so difficult to sell to discerning buyers. The improvement of the color and the clarity of these low quality stones is therefore of extreme importance to the trade. Research in material science has now given us the ways to improve the appearance of gemstones permanently and there is indeed considerable enhancement in the value of gemstones after treatment. On the other hand, there are people who have voiced serious objections to altering what nature has provided. It is a fact though that man is constantly improving on nature to make profits for himself, whether it is plastic surgery or gemstone enhancement.
There are many techniques used to enhance the color and quality of gemstones. Radiation treatment using gamma rays, electrons, x-rays are few. The most famous method of gemstone treatment is heat treatment. Specially corundums are heat treated to produce bright color blue sapphires. Heat treatment is a very popular method for enhancing colors of sapphires. Heat treatment to standards are accepted by the trade.
Sri Lanka (Ceylon) Emerald Gemstones
The emerald belongs to the mineral family of beryl, being chemically a silicate of beryllium and aluminium. Other members of the beryl family include the cheaper blue aquamarine, pale pink morganite, golden heliodor and pale green beryl. The emerald has always been treasured for its rich green color. Its name originated from the Persian but later the Greeks called it smaragdos and later still smaragdus. This name slowly became esmeraude, then emeraude and emeralde and the Anglo-Saxons of the sixteenth century settled on the present name of emerald. Archaeologists uncovered emeralds in Egyptian and Etruscan sites more than a century ago. The gems were traded in Babylon around 2000BC and between 3000 and 1500BC the Pharaohs of Egypt wore emeralds taken from the now exhausted mines near the hills of Jebel Sikait bordering the red sea.
The ancients believed that the stone symbolised love and rebirth, immortality and courage. It sharpened the intelligence and improved the working of the heart. The gem became the stone of Venus, and it was said that it would change colour and break when worn by an adulterer. The Romans said that it was the only gem which delighted the eye without fatiguing it, and the emperor Nero shielded his eyes with emeralds to watch the gladiators.
One legend says that when Lucifer fell from heaven, he lost the emerald from his crown; this was later found and shaped into a bowl which the queen of sheba sent to Nicodemus. Christ used the same bowl at the last super. On the other side of the Atlantic Ocean, the Incas and Aztecs in South America worshipped the emerald as a holy stone and it was used as currency by the local people; thus emerald have been found in places as far apart as Mexico and the Andean ranges. The Conquistadors reported that the Incas had an emerald the size of ostrich egg. When they conquered America, the Spaniards took vast numbers of emeralds to sell in European market.
The ancients believed that the stone symbolised love and rebirth, immortality and courage. It sharpened the intelligence and improved the working of the heart. The gem became the stone of Venus, and it was said that it would change colour and break when worn by an adulterer. The Romans said that it was the only gem which delighted the eye without fatiguing it, and the emperor Nero shielded his eyes with emeralds to watch the gladiators.
One legend says that when Lucifer fell from heaven, he lost the emerald from his crown; this was later found and shaped into a bowl which the queen of sheba sent to Nicodemus. Christ used the same bowl at the last super. On the other side of the Atlantic Ocean, the Incas and Aztecs in South America worshipped the emerald as a holy stone and it was used as currency by the local people; thus emerald have been found in places as far apart as Mexico and the Andean ranges. The Conquistadors reported that the Incas had an emerald the size of ostrich egg. When they conquered America, the Spaniards took vast numbers of emeralds to sell in European market.
Diamonds of Sri Lanka
Of all precious stones, diamond has been and is the most desired, though it does not have the attractive colour of emerald or ruby. Over the centuries this passion for diamonds has endowed the stones with histories that are rich with mysticism, intrigue, adventure and romance. Found rarely in nature, the gemstone is the hardest and most durable material on earth. More important, the mining and sale of diamond has been so rigidly controlled, that the price of the stones has been increasing steadily over the last three centuries.
Chemists and crystallographers have determoned that the diamond is merely pure carbon crystallised in a structure different from that of common graphite and charcoal. As early as 1675 AD, sir Isaac Newton concluded that diamond would burn in air and twenty years later, Averani and Targioni demonstrated this at the Accademia del Cimento of Florence. They put a diamond in the intense heat of a fierce charcoal fire and saw the stone gradually decrease in size and finally disappear.
Millions of years ago, organic material such as trees or other living creatures died and exposed to the heat of those times, became charcoal. This carbon, trapped within molten rock and subjected to intense pressures and temperatures of over 3000C over the thousands of years, slowly crystallised into clear hard diamonds. Natural volcanic eruptions took the material to the surface of the earth. Later, erosion by the sun and rain and other climatic changes broke up the soil containing the diamonds and scattered it and the gemstones over river beds. These 'alluvial' deposits are found on the surface of river beds, on the rough pebbled sea bed or in gravel down to twenty meters beneath the sand. Diamonds are also mined by digging within the bluish ground of 'Kimberlite' from deep inside the earth, down volcanic pipes of around half a kilometers diameter through which molten material once forced its way up. A productive mine usually yields a gram of diamonds from about three-hundred tonnes of ore.
Chemists and crystallographers have determoned that the diamond is merely pure carbon crystallised in a structure different from that of common graphite and charcoal. As early as 1675 AD, sir Isaac Newton concluded that diamond would burn in air and twenty years later, Averani and Targioni demonstrated this at the Accademia del Cimento of Florence. They put a diamond in the intense heat of a fierce charcoal fire and saw the stone gradually decrease in size and finally disappear.
Millions of years ago, organic material such as trees or other living creatures died and exposed to the heat of those times, became charcoal. This carbon, trapped within molten rock and subjected to intense pressures and temperatures of over 3000C over the thousands of years, slowly crystallised into clear hard diamonds. Natural volcanic eruptions took the material to the surface of the earth. Later, erosion by the sun and rain and other climatic changes broke up the soil containing the diamonds and scattered it and the gemstones over river beds. These 'alluvial' deposits are found on the surface of river beds, on the rough pebbled sea bed or in gravel down to twenty meters beneath the sand. Diamonds are also mined by digging within the bluish ground of 'Kimberlite' from deep inside the earth, down volcanic pipes of around half a kilometers diameter through which molten material once forced its way up. A productive mine usually yields a gram of diamonds from about three-hundred tonnes of ore.
Colored Stones
Gemstones are of tow kinds. There are those that are mineral in origin and are formed as crystals that grew underground during the formation of our earth. They are generally hard and heavy, have beauty and performance and if they are rarely found, they become classed as precious stones. Of these diamonds, emerald, ruby and sapphire are the most popular. Other rare and expensive stones are opal, alexandrite, and newly discovered tanzanite.
An austrian mineralogist named F.Mohs developed a scale to measure the hardness. This so called as Mohs Scale goes from one to ten, the softest being talc with a hardness of one and the diamond, the hardest known stone given a measure of hardness ten. The hardness is measured by scratching the sample with a diamond point and examining the depth of the resulting wound. A second parameter is the heaviness or specific gravity but this is merely the density of the gemstone and not related to the hardness.
Of the organic stones, the rarest are amber and corel but these are not very popular in India and Sri Lanka. There are over thirty popular varieties of precious and semi-precious gemstones in a range of colors, many of which are rare collector’s items.
The usual practice is to cut the rough stone into a desired shape and polish it to obtain the best luster possible.It is then set into a metal frame that holds the gemstone securly and enhances its qualities. The metal generally used include silver, gold and platinum. Pure gold of 24 karat and sure silver of 100 percent are very soft and gems set in these pure metals can easily fall out when the piece of jewelry is in regular use. Jewelers therefore prefer to mount precious stones in gold of 22 karat or in sterling (92.5 percent) silver.
An austrian mineralogist named F.Mohs developed a scale to measure the hardness. This so called as Mohs Scale goes from one to ten, the softest being talc with a hardness of one and the diamond, the hardest known stone given a measure of hardness ten. The hardness is measured by scratching the sample with a diamond point and examining the depth of the resulting wound. A second parameter is the heaviness or specific gravity but this is merely the density of the gemstone and not related to the hardness.
Of the organic stones, the rarest are amber and corel but these are not very popular in India and Sri Lanka. There are over thirty popular varieties of precious and semi-precious gemstones in a range of colors, many of which are rare collector’s items.
The usual practice is to cut the rough stone into a desired shape and polish it to obtain the best luster possible.It is then set into a metal frame that holds the gemstone securly and enhances its qualities. The metal generally used include silver, gold and platinum. Pure gold of 24 karat and sure silver of 100 percent are very soft and gems set in these pure metals can easily fall out when the piece of jewelry is in regular use. Jewelers therefore prefer to mount precious stones in gold of 22 karat or in sterling (92.5 percent) silver.
Caring for Gemstones
Men and women buy gemstones to set in jewellery to be worn and flaunted on special occasions. The brighter and more pure these are, the more they will enhance the beauty of the whole piece and naturally of the wearer too. Great care should therefore be taken to store and clean precious jewelry after wearing them. Gems and gemstones set ornaments therefore need to be carefully chosen and carefully worn, cared for, properly stored, and cleaned with caution to keep them valuable and in good condition for as long as possible.
Choosing Jewellery - Rings and bangles are used constantly and do get knocked around even if worn only for festive occasions. Gemstones for these pieces should not be brittle or soft. Such stones, as for example, pearls and opals are better set in earrings, pendants or brooches. They can be set for special rings, but even then the stone should be in a closed setting for protection.
Diamonds are often held by four prongs or claws but this is not as safe as a six-prong setting. If one of the claws of a four prong setting breaks, the stone will fall out. When the claws get weak after constant wear, the stone should be reset instead of repairing the claw. Even during setting, the goldsmith should be warned not to over heat the stone, especially where platinum jewellery is concerned. A strong tap with a hammer can break or chip a diamond.
In the case of pear shaped or marquise diamonds, the pointed ends should be covered by the setting, or else the stone may chip off during wear. Closed settings are always safer, but the stone could chip or crack when the jewel is broken up for resetting or redesign. Soft gold such as 22-karat is better for closed settings or else the design should allow the stone to be removed without too much effort by the goldsmith.
Choosing Jewellery - Rings and bangles are used constantly and do get knocked around even if worn only for festive occasions. Gemstones for these pieces should not be brittle or soft. Such stones, as for example, pearls and opals are better set in earrings, pendants or brooches. They can be set for special rings, but even then the stone should be in a closed setting for protection.
Diamonds are often held by four prongs or claws but this is not as safe as a six-prong setting. If one of the claws of a four prong setting breaks, the stone will fall out. When the claws get weak after constant wear, the stone should be reset instead of repairing the claw. Even during setting, the goldsmith should be warned not to over heat the stone, especially where platinum jewellery is concerned. A strong tap with a hammer can break or chip a diamond.
In the case of pear shaped or marquise diamonds, the pointed ends should be covered by the setting, or else the stone may chip off during wear. Closed settings are always safer, but the stone could chip or crack when the jewel is broken up for resetting or redesign. Soft gold such as 22-karat is better for closed settings or else the design should allow the stone to be removed without too much effort by the goldsmith.
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