Diamonds – the World's Most Valuable Gemstones
Where Do Diamonds Come From and Why Are They So Expensive?
Oct 31, 2009
The word diamond is derived from the Greek word adamas, which means unalterable or unbreakable. Indeed, they are the hardest of all known, natural minerals. Pushed upward toward the surface of the earth over billions of years as a result of volcanic eruptions, they are highly resistant to scratching and are often used as cutting tools to perforate other materials, like glass. Hydrofluoric acid would dissolve imitation diamonds, but never the real ones. Getting these gemstones out of the ground and the subsequent cutting and polishing jobs are long and difficult. That's why diamonds carry such hefty price tags.
How and Where Are Diamonds Mined?
Many of the known natural diamond reserves can be found in Africa and Australia. The mining of diamonds on a large scale is done by processes called pipe mining and alluvial mining. The former does not refer to pipes made by people, but by geological formation. Pipes are channels formed by volcanic activity, which serve as a conduit between the earth's crust and mantle. Magma flows through this pathway, carrying with it diamonds that were formed deep beneath the ground under extreme pressure.
Shanks are put into the ground next to these pipes and tunnels are driven into the deepest section of the pipe. Diamonds are not sorted out at this location. Enormous rocks containing diamonds are taken out and then moved to a separation facility.
Alluvial mining is done on beaches and riverbeds. The process involves lots of digging through mud, gravel and sand using shovels, sieves and much of the time, bare hands. Diamonds come from Kimberlites, which are rock formations made by cooled magma. Over time they are eroded by water from streams and rivers. The water can carry the diamonds much further downstream and leave them on riverbanks, or right out into an ocean depending on the topography and the location of the Kimberlites themselves.
How Are Diamonds Cut and Polished?
Cutting a diamond takes a lot of skill. A well cut stone will reflect light within itself, from one facet to another and through the top of the diamond. There are a few basic cutting techniques like cleaving and the use of a grinding wheel called a scaif. Cutting a diamond is a long and painstaking process, which can reduce the original weight of a stone by more than sixty percent.
Diamond saws are steel blades lubricated with oil and diamond dust. They are continuously applied to the saw as the diamond is worked. Diamonds are mounted on a 'dop' or padded holder while the blade works it down to a smaller size. The speed of the saw can be thousands or rotations per minute, and cutting a large diamond can take several weeks.
To polish the diamond, the cutter will place it onto the arm above a rotating polishing wheel. The wheel is coated with an abrasive diamond powder that smoothes the stone as it's pressed against the wheel.
The Four C's
Four factors judge the quality of a diamond.
- Cut – This refers to the geometric proportions of diamond and how it has been cut. A diamond that has been cut too deep or too shallow will be less brilliant, and ultimately, less valuable.
- Clarity – This is how flaws in a diamond are measured. Most diamonds contain tiny birthmarks called inclusions. These interfere with the light passing through them. A diamond that is totally free of inclusions and surface blemishes is quite rare, and extremely valuable.
- Carat – This is the weight of a diamond. One carat is equivalent to 200 mg.
- Color – Even the smallest variation in color can make a big difference. A totally colorless diamond allows light to pass through it easily, resulting in a rainbow colored dispersion.
No gemstone in the world can express human feelings more powerfully than diamonds. They have been given to celebrate weddings, anniversaries and engagements. They are also symbols of success and independence. An estimated 65% of the world's diamonds come from Africa and the revenue from these gemstones play an important role in building hospitals, schools and fighting diseases such as AIDS.
Reference:
diamondfacts.org
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