Like no other

Diamond is like no other substance. Except for certain trace elements like boron and nitrogen, it is composed entirely of carbon, the fundamental building block of all life on earth.

The hardest substance known

Carbon is the key ingredient of graphite, a substance that is exceptionally soft. Diamond, on the other hand, made from the very same core element, is the hardest substance known to man. The dichotomy is resolved when we understand the crystal structure of carbon atoms in diamond.

A quick high-school chemistry revision may be in order. Neutral carbon atoms consist of six protons (positively charged particles), and six electrons (negatively charged particles). Four of these electrons, called valence electrons, are available to bond with neighboring atoms. In diamond, all four electrons bond with adjacent atoms, forming covalent bonds - the strongest type of chemical bond. Each carbon atom is therefore connected to four other carbon atoms, creating a rigid and highly symmetrical crystal structure that provides diamond with its unmatched strength.

Diamond is produced deep within the earth, in an area known as the mantle. Scientific evidence suggests that the mantle was formed about 4 billion years ago. Thus, diamond may very well consist of the oldest elemental carbon found on earth.

Repels water and attracts grease

Diamond is the only substance that can scratch another diamond. It is exponentially harder than the next hardest substance, corundum, of which sapphire and ruby are comprised. Furthermore, diamond repels water and adheres to wax and grease. It is this remarkable property, that allows diamond to be easily separated from other minerals in the mining process.

Amazing density

Carbon has a relatively low atomic weight, yet diamond is amazingly dense - 3.51 grams per cubic centimeter. It took millions of years, a pressure of 55,000 atmospheres and temperatures of 1,400 degrees Celsius to produce diamond.

Superior brilliance and luster

In addition to the prized characteristics outlined above, diamond is also well known for its superior brilliance and luster. Like other high density materials, diamond has a high refractive index (ability to bend/slow light). When passing through diamond, light slows to a leisurely 77,000 miles per second. Diamond's high refractive index - 2.42 compared to 1.52 in glass - is also a good prognosticator of its high reflectance (ability to reflect light). Diamond also has a high coefficient of dispersion. When white light passes through a diamond, it is separated into a rainbow spectrum. When the different wavelengths of light interact with the diamond, the shorter wavelengths like blue are bent more than the longer wavelengths like red. This property produces an effect called "fire".

Excellent thermal conductor

Except for some very rare examples, most diamonds are poor electrical conductors. However, diamond possesses excellent thermal conductivity. When diamond is referred to as ice, it is meant quite literally. Diamond has four times the thermal conductivity of copper, itself a superb conductor. When diamond is put to the lips, it draws heat away from the body, making diamond feel cold to the touch.

The most celebrated

Unmatched in hardness, able to repel water and attract grease, of superior density, exhibiting unmatched brilliance and luster, highly reflective, and thermally conductive, diamond has earned its place as the most celebrated and extraordinary gemological specimen in nature.

About the Author

Barry Kaplan is a diamond and jewelry specialist with Gemnation and has authored several published articles and newsletters concerning diamonds, gemstones and the jewelry industry.