Formed to What Their Value Is as Term Paper
- Length: 5 pages
- Subject: Geography
- Type: Term Paper
- Paper: #26133361
Excerpt from Term Paper :
formed to what their value is as well as the characteristics of diamonds.
Diamonds are forever! They are the most beautiful, extraordinarily brilliant, hardest, and highly desired out of all the gems. The word "diamond" holds many different meanings for many different people. The meaning of the gem depends on the occasion or interest one holds in the gem. On wedding and engagement ceremonies, diamonds are given to the couple because for one's fiancee or wife, a diamond is symbolizes purity and commitment to never-ending love. We often hear the brand mantra of De Beers "A Diamond is Forever." For the Sports Fan, a diamond is the focus of American baseball; to the gambler or bridge addict, it signifies a suit of playing cards; to the rich and famous, the commodity represents wealth and status; to the monarchist, its beauty, rarity and durability symbolize royalty. However, the question we should ask ourselves is 'what is diamond'? Where is it found? How does is it found in the environment in its raw form? How is it formed? The following text answers these questions to satisfy the individual reader, especially if the reader's knowledge is limited to the engagement ring and other ways of suing diamonds in jewelry. [McCarthy, J.R.: Fire in the Earth - The Story of the Diamond]
Basically people have knowledge of gem quality diamonds that is restricted to what we know as the four "Cs"-Clarity, Carat (weight), and Color and "Cut," which also establish its value in the market place. Diamond is the world's hardest substance, which is quite surprising because unlike the extremely soft mineral graphite, it is just made up of only one element, which is carbon. Although, diamond and graphite have the same compositions but the two minerals differ widely in their physical properties. This is due to the difference in how the atoms are arranged in both minerals. The most pronounced contrast is exhibited in color, transparency while the other features simply reflect a difference in the structure of the crystal, that is, how the carbon atoms are arranged and packed in the crystal lattice.
The difference in the crystal structures of graphite and diamond are shown in figure 2. In figure 2(a), we can see a 'ball -- and stick' illustration of the graphite structure. The structure shows the carbon atoms to be arranged in sheets of six-member rings. The diagram illustrates how the sheets are loosely held together. The fact that the layers are loosely held together is what characterizes graphite to be soft and surprisingly slippery. The structuring of the layers is what allows them to slide over one-another. This property of graphite makes it an excellent lubricant; it is also being used as an alternative for grease and other lubricating products. Figure 2(b) shows the diamond structure. The carbon atoms are rigidly bound to each other through the sharing of electrons in a cubic pattern. This arrangement characterizes for the mineral's unusual and unexpected hardness as well as other distinguishing properties. [Kraus, E.H., Hunt, W.F., Ramsdell, L.S., Mineralogy - An Introduction to the Study of Minerals and Crystals.]
Diamonds were discovered in India over 2000 years ago, where the diamonds became a source of commercial trade until they were discovered in Brazil in 1730. In the countries it was discovered in, diamonds were found in the alluvial deposits of sand and gravel. The deposits are called "secondary deposits," since they were formed from the erosion of bedrock or "primary" sources. As far back as the 1960's, more than 80 per cent of world production of diamonds came from alluvial or secondary sources. Other sources of primary deposits consequently were discovered in South Africa in the 1870s; in Russia in the 1950s; in Botswana in 1966; followed by Australia in 1979, which has the world's largest diamond producer in the Argyle mine. Discovery of diamonds is rather new in Canada, where they were discovered in 1991. After so many years of discovery, diamonds are now being produced in more than 20 countries, with an annual production of about 110 million carats by weight. In an analysis conducted by the U.S. Bureau of Mines it was found that almost half of the diamonds marketed between the years 1985 and 1990 were of 'gem' or 'near-gem' quality. [Schumann, Walter, Gemstones of the World]
Diamonds are found in pipes or what is called "diatremes." The pipes or diatremes are made up of the rock known as kimberlite; this peculiar rock consists of olivine, serpentine, mica, ilmenite, carbonates and other minerals. It was named kimberlite since it was discovered at Kimberley, in South Africa. The diamondiferous kimberlite pipe is a rare, complex lithological mix of three components: (1) kimberlite, which forms a matrix to (2) fragments of one or both of rocks known as eclogite and peridotite and (3) pieces of sedimentary and other country rocks. The kimberlite matrix is an igneous rock that forms into a crystal from magma that is produced deep down in the Earth. The structure of eclogite is made up mainly from the minerals garnet and pyroxene, and peridotite, which are composed of the minerals olivine and pyroxene, and they are also found deep within the earth. Although, the kimberlite matrix contains diamonds in small quantities, inclusions of eclogite and peridotite could contain nearly 10% by volume. The diamonds found in ecolgite and peridotite, whereas, those found in the kimberlite matrix are secondary. The World's kimberlite pipes are found as upward-expanding cones represent the previous volcanoes. [Kraus, E.H., Hunt, W.F., Ramsdell, L.S.: Mineralogy - An Introduction to the Study of Minerals and Crystals]
Figure 5: Cross section through a hypothetical model of an inverted cone-shaped kimberlite pipe, showing zonal classification and interpreted surface erosion levels of various mines. Inclusions (xenoliths) may be of eclogite, peridotite, and/or country rocks.
Therefore the characteristics of Diamond are:
Hardness = 10
Crystal System = cubic
Diamond has four good cleavages; this is why diamonds can be shaped when pressure is applied. [Anderson, B.W., Gem Testing]
There are two kinds of diamonds, one is synthetic and the other one is a diamond simulant. It is extremely important to know the difference between the two types of diamonds. The synthetic diamond basically comprises of man-made diamond, which had carbon atoms arranged in the natural diamond structure while the diamond simulant is not a carbon compound with the typical diamond structure. The most common simulants are:
YAG = yttrium aluminum garnet
GGG = gadolinium gallium garnet
CZ= cubic zirconia
Simulants can be distinguished from diamonds using measurement or on the basis of their properties that include:
Read through effect"
For anyone buying diamonds, it's important to know that most gemstones can tolerate high temperatures without being affected by any degradation. One of the three attributes that gemstones must have so as to be categorized, as a gem is the property related to durability whereby diamonds must be able to resist degradation. Gemstones that cannot resist the pressures of the lapping wheel or the heat of a jeweler's torch are not used in making jewelry because they cannot be shaped or provide durability. Original mineral gemstones are made deep within the earth and also from fire when put under extremely high pressures and heat. They also have melting points that exceed 1000 Degrees Centigrade. [Anderson, B.W., Gem Testing]
The gemstones made in the laboratories, the diamond stones have exactly the same properties as their natural isotopes. A good example is of corundum, which is one of the most commonly synthesized gems, and bears a melting point of 2050 Degrees Centigrade, irrespective of being natural or synthetic. [Anderson, B.W., Gem Testing]
The two main diamond simulants are moissanite and cubic zirconia; they can stand…