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All about the diamond process from start to finish.
Diamonds consist of pure carbon that crystallizes under very high pressure and temperatures up to 2,000 degrees Celsius. Such an environment exists only at depths of 150 to 200 km. There, diamonds are formed. Subsequently the diamonds are driven upwards to the surface of the earth by volcanic eruptions. The volcanic materials in which diamonds are found are called "Kimberlite" and "Lamprote".
Sources of Diamonds [ TOP ]
Until the 18th century, India was the only source of diamonds in the world. In the second half of the 19th century, the first diamonds were discovered in Africa. The most important suppliers today are Australia and Zaire for industrial diamonds and Southern Africa for gem quality stones. The Soviet Union is also very important on the world market. At present, the diamond producing countries in order of importance are: 1. Australia, 2. Zaire, 3. U.S.S.R., 4. Botswana, 5. Southern Africa.
Mining [ TOP ]
The mining methods are very diverse, depending on how diamonds present themselves at the earth's surface. The mining of Kimberlite pipe involves open-pit or "underground mining". When freed by erosion from Kimberlite matrix diamond crystals are carried along by rivers. These alluvial diamond deposits are mined by pick and shovel methods: "alluvial mining". Exploitation of sandy coastal strata is done by open terrace construction: "marine mining". Finding diamonds can thus be the result of large industrial operations, but also of small-scale methods, or even manual labor. Diamonds are rare. It is not unusual that 250 tons or rock, sand and gravel must be moved to yield one carat of diamond. The annual world production amounts to approximately 100 million cts of which only 50% are of gem quality.
Diamond Processing [ TOP ]
The diamond obtains its final shape and brilliance by a succession of processes.
Each diamond is unique. Therefore it has to be studied in detail in order to determine the most advantageous manner of processing it, with a minimum loss of weight while obtaining the best possible clarity.
Cleaving
Cleaving is the process of splitting a stone into two pieces to remove impurities or irregularities.
Sawing [ TOP ]
Sawing is done against the grain. Before the diamond is sawn, the marked stone is set in a copper dop with s special kind of paste, consisting of a mixture of plaster and glue. After drying, the paste is hardened and the dop is mounted on the saw. The extremely thin saw blade made of phosphor bronze, is coated with diamond powder mixed with oil. It rotates at a speed of 15,000 to 17,000 turns a minute. The diamond is sawn slowly (2 mm per hour). A large stone can sometimes take days or weeks.
Bruting or Girdling [ TOP ]
Normally, cleaved, sawn or whole stones are bruted to give them their final outline. To do this, the diamond is mounted in a dop, on the chuck of the lathe. The desired form is achieved by turning the diamond against another diamond mounted on a bruting stick. The diamond powder that is produced during the process is carefully collected to be reused.
Polishing [ TOP ]
Polishing a diamond means making a number of facets on the surface of the rough stone. These facets are obtained by using a polishing tang and an adjustable polishing dop. By correctly placing the tang on the polishing wheel, a horizontal circular cast iron disc, the polisher can give the stone its shape and luster.
New Technologies [ TOP ]
It has become imperative to develop new techniques in order to improve the productivity of the diamond industry. A successful technological innovation developed in Antwerp is the manual bruting machine designed for the bruting of rather small goods. Bruting is a process to give the diamond a final outline.
Education and Craftsmanship [ TOP ]
These are of the greatest importance. Only very good proportions and very good finishing result in the gorgeous "Antwerp Cut". The craftsmanship of the diamond industry located in Antwerp and the Kempen has been world famous for over 5 centuries. To maintain this important position Antwerp has to see to it that the quality label "Antwerp Cut" remains a familiar notion throughout the world. Therefore several diamond schools have been founded in order to continue the tradition and to train pupils to become skilled craftsmen.
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