Diamond is the purest allotrope of carbon. In its purest form, diamond is a colourless, lustrous, crystalline solid. Diamonds are usually coloures, some are tinged yellow, some blue, brown, green, pink and even black. This colour is due to some impurity. The grey or black variety of diamonds is known as carbonado and bort. Actually, diamonds are nothing but crystallized carbon atoms. Their brilliance and beauty depend upon the skill with which they are cut and polished. Crystallization of carbon atoms takes place under great heat and pressure.
India was once famous for its diamonds. Today, the major source of diamonds is a region in South Africa. Africa produces nearly 70% of the world’s supply of diamonds. South America, Siberia and Brazil also have diamond mines.
After many years of research, scientists have been able to make small diamonds by compressing carbon under extremely high pressure and temperature. Diamonds so prepared are called synthetic or artificial diamonds. Synthetic diamonds are widely used in industry in cutting and grinding tools. The chemical properties of synthetic and natural diamonds are the same.
Structure of diamond:
Diamonds usually have eight sides forming double pyramids. Some have six sides and they form cubes.
In a regular diamond structure, each carbon atom is held firmly in place by four bonds. These carbon bonds are the strongest bonds to be found in any substance at ordinary temperature.
Properties of diamond:
Diamond has some very interesting properties.
1. It is the hardest substance known.
2. It has a high refractive index 2.415, which gives it an extraordinary brilliance.
3. The specific gravity of diamond is 3.52.
4. Diamond is a bad conductor of heat and electricity because it lacks free electrons. This is because all the four valence electrons are paired and used in the formation of four single covalent bonds with other carbon atoms. Electricity is a flow of electrons and as diamond dies not have free electrons, it cannot conduct heat and electricity.
5. Natural diamond is transparent to X-rays whereas artificial diamond is opaque to X-rays. This property is used for distinguishing artificial and natural diamonds.
6. Chemically, diamonds are un-reactive under ordinary conditions. They remain unaffected by acids, alkalis, organic compounds, etc.
7. Diamonds are insoluble in all liquids.
Uses of diamonds:
The important of diamonds are as follows.
1. Diamonds are valuable gemstones. Larger and purer the diamond, the more valuable it is.
2. Smaller pieces of diamonds are used for cutting glass and drilling rocks. Only a diamond can cut another diamond. Diamond dust is used for polishing diamonds and precious stones.
3. Carbonado and bort are used for making precision instruments.
4. Diamond dies are used to make thin tungsten wires.