Thursday, February 26, 2009
Naturally-occurring features called inclusions provide a special fingerprint within the stone. Inclusions are natural identifying characteristics such as minerals or fractures, occurring while the diamond was being formed in the Earth.The majority of these natural birthmarks are invisible to the naked eye, yet they affect the way light is reflected and refracted within the stone. Inclusions appear as different shapes, such as crystals, clouds or feathers. These idiosyncrasies often add to the overall character of the diamond. Containing several birthmarks or inclusions, the Excelsior is considered one on the world's most beautiful diamonds.Most inclusions are not visible to the naked eye unless magnified.To view inclusions, gemologists need to use a magnifying loupe that allows them to see a diamond at 10x its actual size.Inclusions are ranked on a scale of perfection, known as clarity. The clarity scale, ranging from F (Flawless) to Included (I), is based on the visibility of inclusions at a magnification of 10x. Even with a loupe, the birthmarks in the VVS (Very, Very Slightly Included) to VS (Very Slightly Included) range can be very difficult to find. It is only when a diamond is graded 'I' that it is possible to see the birthmarks with the naked eye. The position of inclusions can affect the value of a diamond and you should consider the number, size, brightness, nature and position of inclusions. Some inclusions can be hidden by a mounting, and have little effect on the beauty or brilliance of a stone. An inclusion in the middle or top of a diamond could impact the dispersion of light, sometimes making the diamond less brilliant.There are very few flawless diamonds found in nature, making these diamonds much more valuable.
Diamonds can be found in many colors, however white-colored or colorless diamonds remain the most popular.Diamonds are graded on a color scale which ranges from D (colorless) to Z. Warmer colored diamonds (K–Z) are particularly desirable when set in yellow gold. Icy winter white colored diamonds (D–J) look stunning set in white gold or platinum. Color differences are very subtle and it is very difficult to see the difference between an E and an F, for example. Therefore, colors are graded under controlled lighting conditions and are compared to a master set for accuracy. Truly colorless stones, graded D are treasured for their rarity. Color, however, is subjective. The Incomparable, one of the world's most beautiful diamonds, contains hints of brown, smokey amber and champagne colors. Nature has also created diamonds in shades of blue, green, yellow, orange, and pink. Red is the rarest of all. These diamonds are called ‘coloured fancies’ and are extremely rare and highly treasured.
Often mistaken with size, carat it is actually a measure of weight.The term carat is a derivative of the word carob. Carob seeds, which are surprisingly uniform in weight, were used as a reference for diamond weight in ancient civilisations. One carob seed equalled one carat.
One carat is equivalent to 200 milligrams. One carat can also be divided into 100 ‘points’. A .75 carat diamond is the same as a 75-point or 3/4 carat diamond.Since larger diamonds are found less frequently in nature, a single 1-carat diamond will cost more than two 1/2-carat diamonds, assuming the colour, clarity and cut are the same.Cut and mounting can make a diamond appear larger or smaller than its actual weight. A diamond’s setting should always optimise its beauty.
Diamond cutting requires great skill and training. The cutter must polish tiny surfaces known as facets onto the rough diamond. This process is what creates the facets known as the crown, culet, table, girdle and pavilion of the diamond.To cut a diamond perfectly, a craftsman will often need to cut away more than 50% of the rough diamond.A well-cut diamond will internally reflect light from one mirror-like facet to another and disperse and reflect it through the top of the gem. The facets, when arranged in precise proportions, will maximize the fire life and brilliance of a diamond.A well-cut diamond will be higher in quality and value than deep or shallow-cut diamonds. Diamonds that are cut too deep or too shallow lose or leak light through the side or bottom, resulting in less brilliance and a less valuable stone. Cut also refers to the shape of a diamond – round, square, or pear, for example.Round diamonds are symmetrical and capable of reflecting nearly all the light that enters, so it is the most brilliant of all diamond shapes and follows specific proportional guidelines.Non-round shapes, also known as ‘fancy shapes’ have guidelines in order that they are considered to be well-cut.
1)First of all, pour some detergent into the water, and mix it till the mixture is full of lather. Remember, the warm water works best.
2) Take your diamond jeweleries, and dip it into the mixture. Leave it dipped for a while, so the dust particles may loose their strength.
3) After five minutes, rinse the jeweleries smoothly for few moments holding with your two-three fingers. While rinsing, the diamonds should be inside the mixture.
4) Now pull your jeweleries out of the detergent solution, and clean them carefully using a soft brush. The use of any hard brush will definitely end up damaging the shine further. In case of the absence of a special diamond cleaning brush, a lipstick brush or a toothbrush may prove handy.
5) Brush all the parts of your diamonds carefully, especially the back of the diamonds. The back becomes the dirtiest as it remains in the constant contact with the sweating skin.
6) Then, use a clean piece of cotton and wrap it around the diamond jeweleries, so the fabric can absorb the water left on them. It is better to leave them under the fan for a while.
Apart from using detergent solutions, one can use any ammonia-based cleaner to clean the diamonds too. Only it needs to leave the jeweleries in the ammonia solution for 5-6 hours before cleaning up with a brush.
The value of a star sapphire depends not only on the carat weight of the stone but also the body color, visibility and intensity of the asterism.
The Star of India is thought to be the largest star sapphire in the world and is currently on display at the American Museum of Natural History in New York City. The 182 carat (36.4 g) Star of Bombay, housed in the National Museum of Natural History, Washington D.C., is a good example of a blue star sapphire.
The rarest of all padparadschas is the totally natural variety, with no beryllium or other treatment, and no heating. To find a stone that is certified by a reputable lab as being completely natural is extremely rare and the stone will be very expensive. High quality, unheated and untreated natural padparadscha sapphires will start off in the range of $5,000 per carat and rise by size, color, tone, cut, and clarity, to $20,000–30,000 per carat.
Blue sapphires are evaluated based upon the purity of their primary hue. Purple, violet and green are the normal secondary hues found in blue sapphires. Violet and purple can contribute to the overall beauty of the color, while green is considered a distinct negative. Blue sapphires with no more than 15% violet or purple are generally said to be of fine quality. Blue sapphires with any amount of green as a secondary hue are not considered to be fine quality. Gray is the normal saturation modifier or mask found in blue sapphires. Gray reduces the saturation or brightness of the hue and therefore has a distinctly negative effect.
The color of fine blue sapphires can be described as a vivid medium dark violet to purplish blue where the primary blue hue is at least 85% and the secondary hue no more than 15% without the least a mixture of a green secondary hue or a gray mask.The 422.99 carats (84.60 g) Logan sapphire in the National Museum of Natural History, Washington D.C. is one of the largest faceted gem-quality blue sapphires in the world.
Because it is a gemstone, sapphire is commonly worn as jewelery. Sapphire can be found naturally, or manufactured in large crystal boules. Because of its remarkable hardness, sapphire is used in many applications, including infrared optical components, watch crystals, high-durability windows, and wafers for the deposition of semiconductors, such as GaN nanorods and blue LEDs.
Sapphire is one of the two gem varieties of corundum, the other being the red ruby. Although blue is the most well known hue, sapphire is any color of corundum except red; red corundum is known as ruby. Sapphire may also be colorless, and it also occurs in the non-spectral shades gray and black. Pinkish-orange sapphire is known as padparadscha.The cost of natural sapphire varies depending on their color, clarity, size, cut, and overall quality as well as geographic origin. Significant sapphire deposits are found in Eastern Australia, Thailand, Sri Lanka, Madagascar, East Africa and in the United States at various locations (Gem Mountain) and in the Missouri River near Helena, Montana. Sapphire and rubies are often found together in the same area, but one gem is usually more abundant.
Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions will indicate that the stone has been treated. Cut and carat (size) also determine the price.Of the world's rubies, the finest are found in Myanmar (Burma). Burmese gems are prized for their hue and high degree of saturation. Thailand buys the majority of Myanmar's gems. Myanmar's "Valley of Rubies", the mountainous Mogok area, 200 km (125 miles) north of Mandalay, is noted for its rare pigeon's blood rubies and blue sapphires. Working conditions in the Mogok Valley are primitive and as such similar to mining conditions in other parts of the world.
Emeralds, like all colored gemstones, are graded using four basic parameters, the four Cs of Connoisseurship; Color, Cut, Clarity and Crystal. The last C, crystal is simply used as a synonym that begins with C for transparency or what gemologists call diaphaneity. Prior to the 20th Century jewelers used the term water as in "a gem of the finest water" to express the combination of two qualities, color and crystal. Normally, in the grading of colored gemstones, color is by far the most important criterion. However, in the grading of emerald, crystal is considered a close second. Both are necessary conditions. A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of to be considered a top gem
1-Darya-e-Noor : The largest pink diamond in the world, about 186 carats (36.4 g), part of
Iranian Crown Jewels. Its exact weight isn't known and 186 carats is an estimate.
2-Tiffany Yellow Diamond: Antique modified cushion-shaped stellar brilliant cut, on display at Tiffany & Co.'s New York City store.
3-Koh-i-Noor: A 105 carat (21.6 g) white of Indian origin, with a long and turbulent history and a good deal of legend surrounding it. After belonging to various Mughal and Persian rulers, it was taken away from the Maharaja Duleep Singh of Lahore and was presented to Queen Victoria during the British occupation of India, and is now part of the Crown of Queen Elizabeth the Queen Mother.
Diamonds can also form in other natural high-pressure events. Very small diamonds, known as microdiamonds or nanodiamonds, have been found in meteorite impact craters. Such impact events create shock zones of high pressure and temperature suitable for diamond formation. Impact-type microdiamonds can be used as one indicator of ancient impact craters.
In 1813, Humphry Davy used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon. Later, he showed that in an atmosphere devoid of oxygen, diamond is converted to graphite. The most familiar usage of diamonds today is as gemstones used for adornment a usage which dates back into antiquity. The dispersion of white light into spectral colors , is the primary gemological characteristic of gem diamonds.
In the twentieth century, experts in the field of gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, cut, color, and clarity.