Saturday, September 5, 2009

Diamonds are a mineral

Diamonds are a mineral, a natural crystalline substance, the transparent form of pure carbon or nearly pure carbon. Diamonds have extraordinary qualities. Diamonds have a broad colour range, high refraction, high dispersion of fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. Diamonds are known as the "king of gems" they glitter, dazzle, and symbolize purity and strength.

A diamond is the oldest thing you will ever own, probably 3 billion years in age, fully two thirds the age of the Earth. A diamond is a strategic and high-tech supermaterial for our technological society. Diamond is the birth stone for the month of April.

A diamond is composed of the single element carbon, and it is the arrangement of the C atoms in the lattice that give a diamond its amazing properties. Both diamond and graphite are composed of just carbon. However a diamond is the hardest known material and graphite is one of the softest, this was caused by a rearrangement of the way the atoms are bonded together. Diamond carbon atoms are linked in a regular three-dimensional lattice with a repeating or crystalline pattern.
Diamond belongs to the cubic, or 'isometric' crystal system. The most commonly seen crystal structures or arrangements are:
• Octahedron (8 faces)
• Cube (6 faces)
• Dodecahedron (12 faces)
A diamond is the ultimate gemstone, having few weaknesses and many strengths. It is well known that diamonds are the hardest substance found in nature, but few people realize that diamonds are four times harder than the next hardest natural mineral, corundum - sapphires and rubies.

Natural diamonds are classified by the type and level of impurities found within them.
• Type Ia diamond - Most natural diamonds are of this type, which contain up to 0.3% nitrogen.
• Type Ib diamond - Very rare (~0.1%) in nature, but almost all synthetic (industrial) diamonds are of this type. They contain nitrogen at concentrations of up to 500 ppm.
• Type IIa diamond - Very rare in nature, these diamonds contain so little nitrogen that it can't be easily detected by the usual IR or UV absorption measurements.
• Type IIb diamond - Extremely rare in nature. These have such a low concentration of nitrogen (even lower than type IIa) that the crystal is a p-type semiconductor (due to uncompensated B acceptor impurities).