Diamond

Diamond and its Properties 

Diamonds are the homogeneous, solid, naturally-occurring and inorganic substances with definite chemical composition of diamond and an accurate internal arrangement of atoms. Diamond has the highest thermal and hardness conductivity of any natural material. These diamond properties are useful in primary industrial uses such as cutting and polishing tools. Diamonds originate under notably high pressure, 150 km deep in the upper mantle. Pure carbon is pressed into the diamond structure. Diamond’s properties are seen in kimberlite pipes. Apart from the hardness, diamond provides a stately compound of physical, chemical, and mechanical properties:

• High electrical resistivity

• Low thermal expansion coefficient

• High strength

• Hardness

• Low coefficient of friction

• High thermal conductivity

• Resistant to chemical corrosion

• Biologically compatible

• Broad optical transparency from ultraviolet to infrared

Natural diamond is carbon crystals that form under high temperature and pressure conditions that exist only about 100 miles beneath the earth’s surface. It is approximately 99.95 percent carbon. The other 0.05 per cent comprises higher trace elements. 

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Chemical composition of Diamond 

Diamond properties have a sizeable covalent formation in which :

• Each Carbon atom is affixed to four different carbon atoms by covalent bonds.

• The carbon atoms possess a general lattice arrangement.

• No free electrons are present.

Physical Characteristics of Diamond 

The essential element of Diamond is Carbon, and Diamonds are mostly yellow or brown in colour. Diamonds in pink, purple, violet or vivid hues of red or orange are scarce and very expensive. Grey, green or black crystals are used for Industrial purposes. The Diamond Streak is known as none or colourless. It has the highest level of lustre for a nonmetallic mineral. The specific gravity of Diamond is 3.4 to 3.6. The melting point of Diamond is almost 4000°C. It cannot conduct electricity as the electrons are held tightly between the atoms and are not free to move. Diamonds are insoluble in water and organic solvents. There are no possible inclinations which could transpire between carbon atoms and solvent molecules which could overweigh the attractions within the covalently bound carbon atoms.

Formation of Diamond

Diamonds form at high pressures and temperatures that transpire in Earth’s mantle about 100 miles beneath Earth’s surface. Most diamonds found are conveyed to Earth’s surface by deep-source volcanic eruptions. These eruptions originate in the mantle and are transferred to the Earth’s surface without melting. The blocks from the mantle are identified as xenoliths. It contains diamonds that are developed at the high pressure and temperature conditions of the mantle.

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Optical Properties of Diamond 

Diamond is a crystal that is translucent to opaque and which is commonly isotropic. The four main optical characteristics of diamonds are optical absorption, lustre, fluorescence and colour. 

• Fluorescence:  Diamonds display fluorescence, that is, they emit light of different colours and fervour under long-wave ultraviolet light (365 nm). 

• Optical absorption: Some diamonds have a noticeable absorption spectrum consisting of a fine line in the violet at 415.5 nm; however, this line is frequently invisible till the diamond has been cooled to moderate temperatures.  

• Colour:  Diamonds transpire in different colours: brown, yellow, grey, black, white, blue, orange and red. Coloured diamonds include crystallographic defects, including structural defects and substitutional impurities that induce the colouration. Theoretically, pure diamonds would be transparent and colourless. There are scientifically two diamond class: 

• Type I diamond has nitrogen (N) atoms as the chief impurity, up to 1 per cent concentration. If the N atoms are in larger aggregates or pairs, they do not affect the diamond’s colour. Type ii diamonds have significantly fewer nitrogen impurities.

• Lustre:  The lustre of a diamond is defined as ‘adamantine’, which means diamond-like. Reflections on an adequately cut diamond’s sides are undistorted, due to their flatness. 2.417 is the refractive index of a diamond. Diamond is isotropic because of its cubic structure. Its high dispersion of 0.044 manifests in the tangible fire of cut diamonds.