Presentation on theme: "A Diamond is Forever. A diamond (from the ancient Greek ἀ δάμας – adámas, meaning "unbreakable," "proper or "unalterable") is one of the best-known and."— Presentation transcript:
A diamond (from the ancient Greek ἀ δάμας – adámas, meaning "unbreakable," "proper or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been known to mankind and used as decorative items since ancient times; some of the earliest references can be traced to India. The hardness of diamond and its high dispersion of light – giving the diamond its characteristic "fire" – make it useful for industrial applications and desirable as jewellery. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the four Cs, which are carat, cut, colour, and clarity. Other characteristics, such as presence or lack of fluorescence, also affect the desirability and thus the value of a diamond used for jewellery.
General CategoryNative Minerals Chemical formulaC Strunz classification01.CB.10a Identification Molar mass12.01 g·mol -1 Colour Typically yellow, brown or gray to colourless. Less often blue, green, black, translucent white, pink, violet, orange, purple and red. Crystal habitOctahedral Crystal system Isometric-Hexoctahedral (Cubic) Cleavage 111 (perfect in four directions) FractureConchoidal (shell-like) Mohs scale hardness10 LusterAdamantine StreakColorless Diaphaneity Transparent to sub- transparent to translucent Specific gravity3.52±0.01 Density3.5–3.53 g/cm 3 Polish lusterAdamantine Optical propertiesIsotropic Refractive index2.418 (at 500 nm) BirefringenceNone PleochroismNone Dispersion0.044 Melting pointPressure dependent
Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years. Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history. The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. In 1772, Antoine Lavoisier 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 in 1797, Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas he established the chemical equivalence of these substances. The most familiar use of diamonds today is as gemstones used for adornment, a use which dates back into antiquity. The dispersion of white light into spectral colours is the primary gemmological characteristic of gem diamonds. In the 20th century, experts in gemmology 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, colour, and clarity. A large, flawless diamond is known as a paragon. Natural history: The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 kilobars (4.5 and 6 GPa), but at a comparatively low temperature range between approximately 900–1300 °C (1652–2372 °F). These conditions are met in two places on Earth; in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike.
Diamonds are found all over the world, but 80% of all diamonds come from just seven sources: AngolaAustralia BotswanaNamibia Russia Africa Zaire
Diamond Mining Diamond Mining Diamonds are recovered by way of pipe or alluvial mining. Pipe Mining Pipe Mining Pipe mining refers to the extraction of diamonds from volcanic pipes. Typically, a very large area has to be covered. An average of 250 tonnes of ore must be mined in order to produce a one-carat gem quality polished diamond. Alluvial Mining Alluvial Mining This process involves the extraction of diamonds from riverbeds or ocean beaches. Millions of years ago, at the time the diamond pipes were formed, some diamonds were weathered out of the pipes and carried great distances along rivers and even into oceans.
Green Diamond Green diamonds are rare diamonds, since the natural green color comes from exposure to irradiated particles over eons. Green diamonds are fancy diamonds extremely rare and expensive available in great shapes & colors. Most of the green diamonds are produced from Argyle mine. Champagne Diamond Champagne diamonds are natural colored diamonds produced in wide range of colors from light straw to rich cognac. It belongs to brown diamond family in different colors like Fancy Brown Orange, Fancy Orangey Brown, Pinkish Brown and Yellow Brown. Yellow Diamond Fancy yellow diamonds comes in wide range of shades from light yellow to rich canary color. There are different shades of yellow diamonds available depending upon the lightness and intensity of yellow hue.
Pink Diamond Pink diamonds are the world’s valuable and rarely found diamond. Pink diamonds are considered as treasure of treasures and it is associated with femininity, love and grace. Argyle mine is the world foremost source of supplying 95% of pink diamonds. Pink diamonds produced in India, Brazil and Africa was characteristically light in color. White Diamond White diamond is the leading diamond color produced in wide shapes, sizes and varieties. Diamonds used in gemology are basically transparent with a little tint color. These types of diamonds are known as white diamonds. This is the most common type of diamond. Generally, valuable types of diamond will be colorless or white diamonds. Blue Diamond Blue diamonds are the most valuable diamonds next to white diamonds or colorless diamonds. Blue colored diamonds are popularly referred as “Hope Diamonds”. Blue diamonds ranges from pale blue of winter day to deep hue of peacock tail. This is one of the fancy diamonds available in wide shades, shapes and sizes. Some blue diamonds have an ability of conducting electricity.
Carat Diamonds and Gemstones are weighed in metric carats. One carat diamond is equal to 0.2 grams weighing. The value of diamond increases with carat size, but two diamonds with equal weights can have different values depending upon the other three characteristics of diamonds Cut, Clarity and Color. Color Diamonds are valued on their colorlessness. The less color, the higher the value. Diamond color ranges from colorless to yellow. The GIA’s Color Grading Scale for diamond is the industry standard. The scale begins with the letter D representing colorless and continues by increasing the color to letter Z. In GIA’s color grading scale, each letter grade has a defined range of color appearance. The color distinction makes a very big difference in diamond quality and price.
Cut Cut is the important factor in diamond 4 C’s. It is a factor that fuels diamond’s fire, sparkle and brilliance. The traditional 58 tiny facets in a diamond, each precisely cut and sharply defined may be two millimeters in diameters. But without this precision, diamond wouldn’t be as beautiful. The allure of diamond depends more on cut than anything else. It’s difficult to analyze that the cut of any diamond has three attributes brilliance, fire and scintillation Clarity In diamonds, clarity refers to absence of inclusions and blemishes. Since diamonds occurs deep under the surface, most diamonds contains unique birthmarks called (internal) inclusions and (external) blemishes. Diamonds without birthmarks are rare and its rarity affects the value. GIA’s International Diamond Grading System has developed a clarity grade for diamond that ranges from flawless (FL) to diamond with obvious inclusions (I3).