Difference between revisions of "Diamond"

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[[Image:Hope_Diamond.jpg|left|framed|The Hope Diamond]]<br clear="left" />
  
 
Diamond is a polymorph (many forms) of the element carbon. Graphite is another polymorph.  
 
Diamond is a polymorph (many forms) of the element carbon. Graphite is another polymorph.  

Revision as of 08:24, 4 December 2006

Diamond
Chemical composition C
Crystal system Cubic
Habit Octahedral, cubic
Cleavage Perfect (octahedral)
Fracture Conchoidal
Hardness 10
Optic nature Isotropic
Refractive index 2.417
Birefringence None
Dispersion High, 0.044
Specific gravity 3.52
Lustre Adamantine
Pleochroism None
The Hope Diamond

Diamond is a polymorph (many forms) of the element carbon. Graphite is another polymorph. The two share the same chemistry, pure carbon, but have very different structures and properties. Diamond is hard, Graphite is soft (the "lead" of a pencil). Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. Diamond is the ultimate abrasive, Graphite is a very good lubricant. Diamond is transparent, Graphite is opaque. Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system. Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. In fact, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow.

Diamonds have long been valued for their hardness and incredible brilliance. Chemically a diamond is pure carbon, just like the graphite used in pencils. Diamonds' hardness is the result of extremely strong chemical bonds between the carbon atoms. Although most people think of diamonds as colorless, they actually occur in almost every color. Diamonds were viewed as talisman by the ancient Hindus in India, which is where diamonds were first discovered. The most powerful stones were thought to be naturally occurring octahedrons of exceptional clarity that exhibited fire. These stones would bring the owner power, wealth, everlasting youth and good fortune. It was believed that flawed or inclusive stones could have quite the opposite effect. During the first century AD prominent Romans wore uncut diamonds set in rings also as talismans. For hundreds of years it was believed that diamonds had gender. As late as 1566, Francois Ruet described two diamonds as having offspring. The first diamond engagement ring was given to Mary of Burgundy by Maximillian in 1477.

Color

All colors.Diamonds most commonly occur in shades of yellow and brown. The rarer stones are colorless and the rarest are reds, blues, pinks, greens in intense saturation.

Durability

Diamonds are the hardest of all gemstones. That refers to their ability to scratch. But they can be broken along their four planes of inherent cleavage.

Localities

Diamond deposits are found world wide. The most noteable being Africa, Australia, India and most recently Canada.

Synthetics

Swedish and American researchers discovered how to synthesize diamonds in the 1950's. Currently, the two methods used to synthesize diamonds are High Pressure, High Temperature (HTHP) and Chemical Vapour Deposition (CVD).

Imitants

Cubic Zirconia, Moissanite, etc

External links