DIAMOND: THE EARTH'S HARDEST MINERAL

DR. S. M. ALAM
(feedback@pgeconomist.com)

Oct 24 - 30, 2011

Diamond is the world's hardest mineral. It can cut into pieces all the items exist on the earth, but not a single item can cut diamond into pieces. It has 10 Mho's scale of hardness scale.

Impure form of diamond known as 'corundum' is used for cutting all the items as. Contrary to diamond, talc is the softest mineral in the world and it has 1 Mho's scale of hardness and therefore talc is used for making talcum powder all over the world.

Diamond is a fascinating mineral. It is chemically resistant and it is the hardest known natural substance. These properties make it suitable for use as a cutting tool and for other uses where durability is required.

Diamond also has special optical properties such as a high index of refraction, high dispersion, and high luster. These properties help make diamond the world's most popular gemstone.

Gemstone diamonds are stones with color and clarity that make them suitable for jewelry or investment use. These stones are especially rare and make up a minor portion of worldwide diamond production. Gemstone diamonds are sold for their beauty and quality.

Industrial diamonds are mostly used in cutting, grinding, drilling and polishing procedures. Here, hardness and heat conductivity characteristics are the qualities being purchased. Size and other measures of quality relevant to gemstones are not important. Industrial diamonds are often crushed to produce micron-sized abrasive powders. Large amounts of diamonds that are of gemstone quality but too small to cut are sold into the industrial diamond trade.

Diamonds have a very high luster. The high luster is a result of a diamond reflecting a high percentage of the light that strikes its surface. This high luster is what gives diamonds their pleasing sparkle. Diamond also has a high dispersion. As white light passes through a diamond, this high dispersion causes that light to separate into its component colors. Dispersion is what enables a prism to separate white light into the colors of the spectrum. This property of dispersion is what gives diamonds their colorful fire. The quality of a diamond gemstone is primarily determined by four factors: color, cut, clarity and carats.

Diamonds are one of the world's most precious gems. The word diamond comes from a Greek word, adamus, which means invincible. This is because diamonds are the hardest minerals in the world. They are 1000 times harder than rubies or sapphires. Not even the most powerful acids can harm a diamond's surface.

Diamond is a rare, naturally occurring mineral composed of carbon. Each carbon atom in a diamond is surrounded by four other carbon atoms and connected to them by strong covalent bonds. This simple, uniform, tightly bonded arrangement yields one of the most durable substances known.

The following countries produced equal to or more than one million carats of diamonds in 2008: Botswana (25 million carats); Russia (23 million carats); Canada (17.5 million carats); Angola (10 million carats); South Africa (6 million carats); Congo (5.5 million carats); Namibia (2.5 millions carats), Guinea (1 million carats).

In the 1960's, diamond fields were discovered in Botswana. The three diamond mines - Orapa, Letlhakane and Jwaneng - make Botswana the world's second-largest producer of diamonds and the largest producer of gem diamonds by both value and number.

In 1991, a diamond-bearing kimberlite pipe was drilled at Lac de Gras, N.W.T., Canada to begin the largest land staking rush in Canadian mining history. Production of the BHP/DiaMet pipes began in 1998. Work to date indicates several pipes have gem diamond concentrations and valuations as rich as diamond mines in Africa.

Large diamond deposits were found in Brazil around the 1720's. Huge diamond fields were discovered in Siberia in 1956. In the 1860's, diamonds were found in South Africa. This led to a diamond rush in the Kimberly Fields. Now, most of the world's diamonds come from South Africa.

In 1906, diamonds were found near Murfreesboro, Arkansas. A boom town called Kimberly was formed along the road to the mine. Today, the town of Kimberly is gone and the diamond mine is owned and operated by the state of Arkansas.

Diamonds are made of carbon, the same material that makes coal and the lead in pencils. All life on earth is carbon-based--humans, animals and plants. Diamonds are also the hardest mineral known to man; it is almost 10 times the strength of steel.

Their crystalline structure helps to disperse light, giving diamonds their brilliance. Gem diamonds are used for jewelry and other forms of decoration. Industrial diamonds have many applications, including use in oil drilling. Almost 80 percent of diamonds mined are industrial grade diamonds. To be gem grade, a diamond must meet high standards in clarity and color.

Diamonds are not native to Earth's surface. Instead they form at high temperatures and pressures that occur in Earth's mantle about 100 miles down. Diamonds are brought to Earth's surface by volcanic eruptions. Instead of melting and being transported to the surface as a melt, the diamonds are carried to the surface in large pieces of mantle rock known as xenoliths.

The diamonds are produced either by mining the rock, which contains the xenoliths or by mining the soils and sediments that formed as the diamond-bearing rock weathered away.

Diamonds are the world's most popular gemstones. More money is spent on diamonds than on all other gemstones combined. Part of the reason for diamond's popularity is a result of its optical properties - or how it reacts with light. Other factors include fashion, custom and marketing.

Diamonds have a very high luster. The high luster is a result of a diamond reflecting a high percentage of the light that strikes its surface. This high luster is what gives diamonds their pleasing "sparkle".

Diamond has a high dispersion. As white light passes through a diamond, this high dispersion causes that light to separate into its component colors. Dispersion is what enables a prism to separate white light into the colors of the spectrum. This property of dispersion is what gives diamonds their colorful "fire".

The quality of a diamond gemstone is primarily determined by four factors: color, cut, clarity and carats.

Most gem quality diamonds range from colorless to yellow. The most highly regarded stones are those that are completely colorless. These are the ones sold for the highest prices. However, another category of diamond gemstone is increasing in popularity. These are the "fancy" diamonds, which occur in a variety of colors including, red, pink, yellow, purple, blue, and green. The value of these stones is based upon their color intensity, rarity, and popularity.

The quality of workmanship in a diamond has a large impact upon its quality. This influences not only the geometric appearance of the stone but also the stone's luster and fire. Ideal stones are perfectly polished to be highly reflective and emit a maximum amount of fire.

The ideal diamond is free from internal flaws and inclusions (particles of foreign material within the stone). These detract from the appearance of the stone and interfere with the passage of light through the stone. When present in large numbers or sizes they can also reduce the strength of the stone.

Diamonds are sold by the carat (a unit of weight equal to 1/5th of a gram or 1/142nd of an ounce). Small diamonds cost less per carat than larger stones of equal quality. This is because very small stones are very common and large stones are especially rare.

Because diamonds are very hard, they are often used as an abrasive. Most industrial diamonds are used for these purposes. Small particles of diamond are embedded in a saw blade, a drill bit or a grinding wheel for the purpose of cutting, drilling or grinding. They might also be ground into a powder and made into a diamond paste that is used for polishing or for very fine grinding.

There is a very large market for industrial diamonds. Demand for them exceeds the supply obtained through mining. Synthetic diamonds are being produced to meet this industrial demand. They can be produced at a low cost per carat and perform well in industrial use.

Most industrial diamonds are used as abrasives. However, small amounts of diamond are used in other applications. Diamond is a very stiff material and when made into a thin dome it can vibrate rapidly without the deformation that would degrade sound quality. Most of the world's diamond production is consumed by industry for use as an abrasive in cutting, grinding, drilling, and polishing procedures. The second category of diamond use is as a gemstone. More money is spent on diamonds than all other types of gemstones combined.

Diamonds come in many different cuts, taking on various shapes like a pear cut, (pear-shaped); princess cut (square); round (brilliant cut); marquis cut (football shaped); heart cut (idealized heart shape); trilliant (triangular); oval; and emerald cut (rectangular).

There is also a synthetic industry producing diamonds that churn out 500 million carats annually.

Diamonds are also used in microelectronics as heat-sinks because of their ability to transfer heat away from sensitive circuits. Diamonds are also used in speaker domes, windows for lasers and x-ray machines, as micro-bearings, and as a wear-resistant material for moving parts. The United States is the largest consumer when it comes to buying the gems. America spent about 35 percent of total world consumption on diamond purchases in 2008. Worldwide, $54 billion was spent on the purchase of diamonds in 2008.