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Types of Diamonds

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Types of Diamond Most of us know diamonds as diamonds in jewelry such as wedding rings, diamond earrings, diamond engagement rings, diamond anniversary rings, diamond solitaire rings and 3 stone rings etc. However, diamonds are used for multiple purposes. You will find the following information interesting. Read on..

Natural Diamonds

Natural Diamonds vary depending on their formation process, the kind of inclusions that occur during their formation, creates variations in terms of color and electrical conductivity.

Diamond is composed of the single element carbon, and it is the arrangement of the C atoms in the lattice that give diamond its amazing properties. Compare the structure of diamond and graphite, both composed of just carbon. In diamond we have the hardest known material, in graphite we have one of the softest, simply by rearranging the way the atoms are bonded together.

Type I Diamonds:

This is the most commonly occurring form of natural diamond. They are further classified into type Ia and Ib.

Type Ia:

These diamonds contain about 0.3% nitrogen. Nitrogen absorbs blue light so they have a pale yellow or brown color. About 98% of diamonds come under this category.

Type Ib:

When Nitrogen atoms get uniformly distributed all over in diamond's crystal structure, the overall structure thus formed absorbs green and blue parts of the spectrum. This results in a darker appearance, generally deep yellow, brown, even greenish, canary and orange. These diamonds are very rarely found. About 0.1% belongs to this category. Synthetically produced diamonds are mostly found to be Type1b which contain about 500ppm of nitrogen impurity.

Type II:

These diamonds include very few nitrogen atoms such that the number is insignificant. So the crystal structure has fewer inclusions and this results in a more pure carbon crystal. The presence of nitrogen atoms is difficult to be detected even by Infrared and UV absorption methods. Type II diamonds are rarely found in nature.

Type IIa:

Type IIa diamonds are almost colorless, and have a slight yellowish tint due to the presence of twisted carbon tetrahedrons that were formed while diamond was being transported to the earth's surface. The twisted structures absorb some part of the light and thus result in yellow, brown and sometimes pink and red colors.

Type IIb:

Boron is the impurity found in these diamonds instead of Nitrogen. Boron is known to absorb yellow, orange and red parts of the spectrum, which results in appearance of blue color in these diamonds. But they can also be grayish and sometimes almost colorless. These diamonds are very rarely found.

Green Diamonds:

In their raw and uncut forms, green diamonds are yellowish green characterized by the degree of lubricity. These diamonds show their green color after being cut. The famous collection of De Beers Fancy colored diamonds includes some of the world's most beautiful and rare green diamonds. The color of these diamonds results from being in contact with a radioactive source before being mined at some point of its lifetime under the earth. Prolonged exposure to beta, gamma rays as well as neutron particles present in uranium compounds is believed to be the cause.

The color of these stones is sometimes treated by heating but care is taken to keep the temperature below 600 degrees Celsius, otherwise there are chances of modification of the gem's crystal lattice to give a yellow or brown color to the treated gem. After a treatment the gem's crystal lattice remains permanently distorted.

These diamonds are generally found in alluvial deposits and also found in upper parts of diamond bearing volcanic "pipe". The most famous green diamond is Dresden Green.

Synthetic Industrial Diamonds

Synthetic industrial diamonds are produced by the process of High Pressure High Temperature Synthesis (HPHT). In HPHT synthesis, graphite and a metallic catalyst are placed in a hydraulic press under high temperatures and pressures. Over the period of a few hours the graphite gets converted to diamond. The resulting diamonds are usually a few millimeters in size and include a number of flaws which make them unfit for use as gemstones, but they are extremely useful for industrial purposes, e.g. edges on cutting tools, drill-bits and for being compressed to generate very high pressures. (Although used to cut, grind, and polish many materials, diamonds aren't used to machine alloys of iron because the diamond (carbon) reacts with iron at high temperatures).

Thin Film Diamonds

Chemical Vapor Deposition (CVD) process is used to deposit thin films of polycrystalline diamond. CVD technology makes it possible to put 'zero-wear' coatings on machine parts. Diamond coatings are used to draw the heat away from electronic components, fashion windows that are transparent over a broad wavelength range, and take advantage of other properties of diamonds.


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