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.
Today, diamonds are mined in at least 20 countries around the world; the majority of diamonds are found in Australia, Zaire, Botswana, Russia and South Africa.
The Argyle Diamond Mine, the world's largest diamond-producing mine, is located in the Kimberley Region of north Western Australia
Monday, July 13, 2009
From myths about valleys of diamonds protected by snakes, to the production of millions of carats in rough diamonds each year, the history of diamonds is one of mystical power, beauty and commercial expertise.
The Middle Ages
As the Indian diamond supply dwindled, smaller finds occurred in Borneo and Brazil, but these were not sufficient to meet the ever-increasing demand for diamonds. The mid-nineteenth century discovery of diamonds near the Orange River in South Africa sparked the world's biggest diamond rush, and helped to satiate the world's increasing appetite for diamonds
During the mid-nineteenth century, diamonds were also being discovered in eastern Australia.
However, it was not until late 1970's, after seven years of earnest searching, that Australia's alleged potential as a diamond producer was validated.
Once a year, Argyle Diamonds issues a special release of outstanding pink diamonds that are sold by special bids in the international and invitation-only, Pink Diamond Tender.
White diamonds are produced by mines all over the world in a wide variety of shapes and sizes.The white diamonds recovered from the Argyle mine are particularly brilliant and of high quality.
The 4C's of colour, cut, clarity and carat weight apply to coloured diamonds just as they do to colourless diamonds except the intensity of colour, not lack of it, plays a greater part in the valuation.
Attractive champagne diamonds with secondary pink colour are also available and command a higher price per carat than champagne diamonds. These stones display slight to bold flashes of pink in their fire.
Argyle Pink Champagne Diamonds are available in three ranges of shades, from light pink champagne to medium and dark pink champagne.
As pink is one of the rarest colours found in diamonds, even secondary colours demand a higher price depending on depth and strength of colour.
Fancy yellow diamonds come in a broad range of shades ranging from light yellow to a rich canary colour.A limited quantity of fancy yellow diamonds is recovered from the Argyle mine.
Limited quantities of fancy blue diamonds are recovered from the Argyle mine.
A limited quantity of fancy green diamonds is recovered from the Argyle mine.
Synthetic moissanite Synthetic moissanite is a new diamond simulant to join the long list of products that imitate diamonds. Although moissanite is being marketed as a new unique, synthetic gemstone, some of its properties are close enough to those of diamonds to lead to confusion in the trade.
Natural moissanite was first identified in a meteorite crater at the beginning of the twentieth century however, most is produced synthetically as natural moissanite is very rare. Chemically, it is 'silicon carbide', also known as 'carborundum', which is widely used for abrasive purposes and for use in the electronics industry.
Synthetic moissanite is a diamond simulant like Cubic Zirconia however, it can be passed as a diamond by the widely used thermal pen testers because it has similar thermal characteristics to diamonds. However, it can be easily identified by other methods.