Sunday, August 9, 2009
Many people don't know that China has diamond mine and for quite a long time as China's 701 Changma diamond mine was opened in 1975. China has produced about 300,000 carats in 2002 and their diamond industry looks to be having great potential despite some problems.701 Changma diamond mine is the largest producer of diamonds in China and is located in the Shandong province.
In its more than 30 years of existence this diamond mine produced over 1 Mct of quality diamonds.Some other provinces are also being explored beside Shandong province (Liaoning, Anhui, Jiangsu and Shaanxi Provinces) as China is well aware of high profits in diamond business and wants to become major player on diamond market.Production in Changma diamond mine increased significantly in last couple of years and considering the findings of new kimberlite pipes in some provinces China is on the right way to become major diamond force in years to come.
Not only China is the large diamond producer but is also among top five consumers of diamond jewelry with and this is increasing because of China's rapid economic growth.Despite China's great potential in diamond industry, China is still not complete certainty for profits in diamond business, since excessive management, external costs, corruption and lack of reliability prevented China's full diamond industry development.
There's also influential underground economy, but with the wise government policy China could and really should benefit from its big potential, as both producer and consumer of diamonds.
Friday, August 7, 2009
Diamondiferous material tends to concentrate in and around 'oxbow lakes,' which are created by abandoned river meanders. These dried 'lakes' receive river water during seasonal flooding which transports large amounts of sediment held in suspension.
The alluvial terrace gravels (below, left) and marine gravels of the south-western coastline of Africa represent the some of the world's largest placer diamond deposits. The world's largest known gem quality alluvial diamond deposits are located along the Namib Desert coastline of southwestern Africa, known as the Sperrgebiet or "forbidden territory," and along the Orange River near Alexander Bay. Namibia's placer diamond deposits are between 40 and 80 million years old, carried from their primary origination point on the Kaapvaal Craton, in central South Africa and Botswana.
Many of these alluvial diamond deposits occur in Pleistocene and Holocene successions (1.8 million to 10,000 years ago). The diamonds within these deposits were transported from deeply-eroded diamondiferous kimberlites or, to a lesser extent, from olivine lamproites formed during the Cretaceous or Permo-Triassic period. Westward draining river systems transported these diamonds to Africa's continental coastline for final deposition within on-shore marine terrace gravels. Diamonds that were transported downstream, but were not deposited on land, made their way to the sea bed just offshore. Diamonds in marine areas are typically trapped in bedrock depressions such as gullies, potholes, depressions, channels or other trapsites for diamondiferous deposits.
Saturday, August 1, 2009
Botswanan Diamond Mines
Jwaneng Diamond Mine
Jwaneng (meaning "a place of small stones") is the richest diamond mine in the world when measured by value of recovered diamonds. The Jwaneng Diamond Mine is located in south-central Botswana about 100 miles west of the city of Gaborone, in the Naledi river valley of the Kalahari Desert. The mine began operations in 1982, and is co-owned by De Beers and the Botswanan government under the name 'Debswana Diamond Company.'
Jwaneng is an open pit mine dug over three kimberlite pipes that converge near the surface. The mine has a very high extraction rate, producing 9.3 million tons of kimberlite ore per year at a ratio of 1.25 carats of diamond per ton. In 2003, the mine produced 14.3 million carats of rough, high-quality diamonds. As of 2005, known reserves will produce at current levels for 27 more years. The Jwaneng mine employs over 2,100 workers.
Jwaneng is the first Botswanan to receive ISO 14001 certification for environmental compliance and has maintained a 5 star NOSA safety rating since 1986. The mine has won multiple national and international safety awards since its inception.
Botswana is a relatively wealthy African country, and has had one of the fastest per-capita income growth rates in the world. Botswana gained its independence in 1966 and has had strong ties to the economy of South Africa for several decades. Botswana's history of diamond mining is commemorated on the 20 and 100 Pula bank notes (below).
There are three additional diamond mines of significance in Botswana. The Lethakane Mine ("little reeds") open pit mine is the second oldest of Botswana's four mines. The Orapa Mine ("resting place for lions") open-pit mine is the oldest of Botswana's mines, located along the 'Orapa Kimberlite Track,' near the boarder with Zimbabwe. The Damtshaa Mine ("water for a tortoise") open pit mine is the other significant mine in Botswana.
AK6 Diamond Mine
De Beers is expecting to have Botswana's first new diamond mine in nearly 26 years, operational by 2008. The AK6 kimberlite deposit is expected to produce up to 1.5 million carats a year.
Friday, July 24, 2009
Thursday, July 23, 2009
Sunday, July 19, 2009
The Nassak Diamond was imported into the United States in 1927, and was considered one of the first 24 great diamonds of the world by 1930. American jeweler Harry Winston acquired the Nassak Diamond in 1940 in Paris, France and recut it to its present flawless 43.38 carats (8.68 g) emerald cut shape. Winston sold the diamond to a New York jewelry firm in 1942. Mrs. William B. Leeds of New York received the gem in 1944 as a sixth anniversary present and wore it in a ring. The Nassak Diamond was last sold at an auction in New York in 1970 to Edward J. Hand, a 48-year old trucking firm executive from Greenwich, Connecticut.
The Nassak Diamond originated in the 15th century in India. Although the date of the original cutting is unknown, the original cutting was performed in India and had sacrificed everything to size while giving the diamond a form and appearance similar to that of the Koh-i-Noor diamond. From at least 1500 to 1817, the Nassak Diamond adorned the statue of Shiva in the Trimbakeshwar Shiva Temple, near Nassak, India, on the upper Godavari River. As priests worshiped Shiva through the statue, the diamond eventually acquired its name from its long term proximity to Nassak, India.
In 1817, the British East India Company and the Maratha Empire in India began the Third Anglo-Maratha War. During the Mahratta war, the Nassak Diamond disappeared from the Shiva statue. The war ended in 1818 and the British East India Company was left decisively in control of most of India.
The Nassak Diamond quickly resurfaced in the possession of Bajirao, the last independent Indian Prince of Peshwa, who handed over the diamond to an English colonel named J. Briggs. In turn, Briggs delivered the diamond to the Francis Rawdon-Hastings, the 1st Marquess of Hastings who had conducted the military operations against the Peshwa. Rawdon-Hastings delivered the diamond to the East India Company as part of the spoils of the Mahratta war. The East India Company then sent the Nassak Diamond to England, to be sold on the London diamond market in 1818.
At the London diamond market, the Nassak Diamond was presented as an approximately 89 carats (18 g) diamond of great purity "but of bad form," having a somewhat pear-shape. The diamond further was characterized as a "rudely-faceted, lustreless mass." Despite its appearance, the diamond was sold for about 3,000 pounds (modernly £173 thousand) to Rundell and Bridge, a British jewelry firm based in London.
In 1831, Rundell and Bridge sold the diamond to the Emanuel Brothers for about 7,200 pounds (modernly £519 thousand). Six years later in 1837, the Emanuel Brothers sold the Nassak Diamond at a public sale to Robert Grosvenor, the 1st Marquess of Westminster. At one point, the Marquess mounted the diamond in the handle of his dress sword. In 1886, the diamond was valued at between 30,000 and 40,000 pounds (modernly between £2.34 million and £3.12 million), due in part to its vast gain in brilliancy from the recut by Rundell and Bridge.
Reguarding its traditional history, which extends 5000 years further back, nothing need be said here; though it has afforded sundry imaginative writers with a subject for highly characteristic paragraphs we have no record of its having been at any time a cut stone."
As a young man Babur owed his survival and success on the political and military battlefields to a combination of winning personal qualities and swift opportunism; these were to insure his conquest of the plains of northern India. But in addition to being a warrior, Babur was a cultured and civilized man - a writer and poet.
The Cullinan II Diamond. Note the two tiny platinum loops on the edges.This is so the stone can be worn as a brooch, alone or with the Cullinan I attached. However, it usually resides in the front of the Imperial State Crown.
Research has disclosed that green or irradiated diamonds are more common from alluvial deposits, although they are found in primary sources, usually in the upper part of the diamond-bearing volanic pipe, but green diamonds of any size are rare. The Dresden Green, which probably weighed over 100 (old) carats in its rough form, is unique amoung world famous diamonds. It was originally probably an elongated unbroken stone since greenish diamonds rarely occur as cleavages.
Thursday, July 16, 2009
Australian Argyle Diamonds are internationally reowned for their unique brilliance and stunning array of colours. Unearthed in the rugged Kimberley region in the far north of Western Australia, Argyle Diamonds thrill in shades of exotic pink, sparkling champagne, rich cognac and dazzling white.
It wasn't until October 2 1979, that geologists were literally standing on top of the richest diamond deposit in the world. They had pinpointed the Argyle Diamond pipe.
What followed was an exclusive programme of drilling, sampling and evaluation. In 1982 the joint venture partners decided to develop a mining operation.
The Argyle Diamond Mine
Argyle Diamond Production
Since its inception, annual production has steadily increased from 29 million carats in 1986, the mine's first full year of production, to 40.9 million carats in 1993. The average annual production since 1994 has been over 35 million carats.
The Argyle diamond mine yields approximately 45 per cent near gem quality, and 50 per cent industrial quality diamonds. The remaining 5 per cent is made up of gem quality diamonds and yields the rare and highly valued pink diamonds, as well as the range of sparkling champagne and rich cognac diamonds.
Argyle's pipe mining operation involves the removal of the diamond-bearing lamproite ore by open-cut mining techniques. The ore is dislodged by blasting and then loaded by excavators into 120-tonne dump trucks. The ore is then transported to the processing plant where the diamonds are extracted. The processing techniques are purely physical and involve crushing, scrubbing, screening and gravity separation of the diamond-bearing ore. Final diamond recovery is achieved by the use of x-ray sorting machines. The machines can detect and remove diamond material because the diamonds fluoresce under x-ray.
Argyle diamonds have two very unique and outstanding features: they are harder than other diamonds and may fluoresce blue under ultra-violet light.
Diamond Sorting Upon reaching Perth, the rough diamonds are sorted. In order to deal with the huge volume of diamonds, Argyle Diamonds has developed new technology. Sorting begins mechanically: the first size sorting of rough diamonds takes place through a series of mechanical sieves.
Argyle Diamonds began polishing diamonds in 1984. Its Perth processing centre is the first of its kind in Australia.
Australian production is staffed by highly-trained crafts-people who employ a combination of traditional methods and modern equipment to unlock the brilliance of rough stones. Argyle uses advanced technology in the form of laser devices, automatic bruting and computerised polishing equipment.
Argyle Diamonds also sends a proportion of its rough diamonds, especially those in smaller sizes, overseas for polishing.
Diamonds need caring to keep them looking at their brilliant best. They should be cleaned at least once a month to keep away the "dullness" that can be caused by skin oils, soap, cosmetics and even cooking grease. The only substance that does not stick to a diamond is water. A clean diamond will reflect better light.
There are several ways of keeping diamond jewellery clean.
The detergent bath is performed with a small bowl of warm suds using any mild liquid detergent. Immerse jewellery pieces in the suds and brush gently with a tooth brush. Rinse under warm running water and pat dry with a soft, lint-free cloth.
The quick dip method uses one of the liquid jewellery care products available. Follow the instructions on the kit.
The latest jewellery-cleaning device is the sonic jewellery cleaner. It is electronically operated and comes with its own solution and directions.
Some extra helpful hints to keep diamond jewellery looking at its best.
It is better not to wear diamond jewellery when doing rough work or the dishes. Despite the durability of a diamond, it can be chipped by a hard blow along its grain.
Take care when doing the housework, not to let diamond jewellery come into contact with chlorine bleach, as it won't harm the diamond but can pit or discolour the mounting.
When placing diamond jewellery in a jewellery case, be sure to wrap them individually as they can easily scratch each other as well as other gem jewellery. Be sure to take all types of precious mounted jewellery to a jeweller at least once a year to check for loose settings and signs of wear
If two identical diamonds are placed side by side and one is less brilliant and fiery than the other, the fault lies in the cutting. Such a stone cannot demand as high a price as a well-cut diamond.
It is important to distinguish between cut and shape. Some of the more popular shapes of diamonds include Round Brilliant, Oval, Marquise, Pear, Heart and Emerald. Within each of these shapes, however, it is the cut that determines the quality of the stone. For example, most diamonds are cut with 58 facets, regardless of their shape.
When nitrogen combines with the diamond crystals during the formation stage it causes a surplus electron in the bonding. This surplus electron absorbs blue light, thus giving off a yellow colour. Yellow diamonds also occur when aggregates of three nitrogens combine and cause surplus bond.
The elements of boron may also be substituted within a diamond during its formation. Boron absorbs red light, hence in the absence of nitrogen, diamonds containing boron are blue in colour. An example of a diamond containing boron is the famous Blue Hope diamond. Diamonds containing boron also exhibit unusual electrical properties and are semi-conductive in nature. Hydrogen is another impurity that, in high quantities, can cause grey or blue colouring in diamonds. However, these diamonds are not semi-conducting.
A vacancy in the regular lattice of atoms within a diamond results in a green colouring. Carbon atoms being knocked out of their regular position by other particles cause vacancies. The depth of colour usually extends about 2mm below the diamond's surface. At extremely high temperatures the vacancies can become mobile and can combine with nitrogen to form other colours such as mauve, orange, blue or gold.
It has been suggested that dislocations in the regular lattice of atoms, caused by severe forces deep in the earth, may be responsible for the brown colouring of champagne and cognac diamonds. The dislocated bonds may affect the light wavelength, thus producing a diamond which is coloured, but which contains no impurities.
It has also been suggested that combinations of dislocations, vacancies, and non-nitrogen impurities cause the much sought-after colouration in pink diamonds. However these theories are still being developed.
Inclusions may not always be visible to the naked eye, however they do interfere with the passage of light through the diamond. Therefore the fewer inclusions a diamond has, the more valuable it is.