What is daimond

one of the purest forms of carbon

Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells.

daimond is a metal

Diamond is a native crystalline carbon that is the hardest known mineral. It is usually nearly colorless. 

When transparent and free from flaws it is highly valued as a precious stone. 

It is also used industrially, especially as an abrasive. Crystallized carbon produced artificially is also called diamond. 

The name diamond is derived from the ancient Greek adamas("invincible"). 

Their hardness and high dispersion of light make diamonds useful for industrial applications and jewelry. 

Diamonds make excellent abrasives, because they can be scratched only by other diamonds, or man-made materials, which also means that they hold a polish extremely well and retain their lustre. 

They have been treasured as gemstones since their use as religious icons in ancient India. Thier 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 marketing campaigns. 

Gem diamonds are commonly judged by the “four Cs”: carat weight,clarity, color, and Cut. 

Approximately 130 million carats (26,000 kg) are mined annually, with a total value of nearly USD $9 billion, and about 100,000 kg of synthetic diamonds are manufactured annually. 

49% of natural diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered inCanada, India, Russia, Brazil, and Australia. They are mined from kimberlite and lamproite volcanic pipes, which brought to the surface the diamond crystals from deep in the Earth where the high pressure and temperature enables the formation of the crystals. The mining and distribution of natural diamonds are subjects of frequent controversy such as with concerns over the sale of conflict diamonds (aka "blood diamonds") by African paramilitary groups. 
 

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A diamond is a stone which can be cut only by a diamond.

A diamond is stone also a mineral which can only be cut by another diamond

Diamond is non metal  made of carbon .It is the hardest substance .