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Processing Gemstones

One of the most difficult parts of being a direct importer of African gems is acquiring high quality gemstone raw material or "rough". The processing of these “rough” gems into the finished product is the most exciting part of the gemstone trail from mine to buyer. Buying expensive parcels of “rough” gemstones is like gambling. Often the rough is purchased when the lighting is poor, or there are other buyers waiting, and a decision has to be made very quickly. Prices can be high. The processing of the gems by highly skilled cutters is often the difference between making money and losing money. Most of Marc'sgemstones are cut by Brazilian cutters who have the best "feel" for the gems. Marc has worked with them for many years. They not only can capture a gemstones best color, brilliance and luster, but also can retain the best weight and shapes for that particular gem variety.

Rough Tourmaline Stones

 This is an incredible lot of rough pink and pastel Zambian tourmaline and blue green tourmaline "dead dog" Namibian deposit. Notice the exceptionally large sizes, clarity and colors. Lots like this come around very seldom. Tourmalines are a gem variety that have unique cutting requirements. In order to optimize the rough, tourmalines have to be cut in elongated shapes such as cushion or emerald cuts. Tourmaline can be suspectible to breaking when being cut so special techniques are applied to avoid breakage.  

The first and most critical step in the processing of rough gems is to remove all fractures and inclusions. This is done with the aid of a high speed diamond sawblade. The thin blade is specially designed to minimize weight loss when making a cut. This process must be done very carefully and thoughtfully, as this step determines the gems shape and size. A wrong cut can mean the difference between a profit and a loss. Here a 15 gram piece of fine blue/green tourmaline is being studied before the initial cut is made.

 Processing Rough Gems  
 

The next step after the sawing is to "preform" the gems into their actual shapes. The preforming is done on a diamond grinding wheel lubricated by water. Depending on the type of gems, the amount of water used is critical. As in this picture, green tourmalines are being preformed, which require lots of water to prevent the gems from getting too hot, which could crack them.

Lusaka, Zambia June 1996 Marc with a local African gem cutter. Many times before Marc purchases gemstone rough from a new locality, he likes to check if the material is stable when cutting. Many types of tourmalines that look OK in the "rough" state crack into tiny pieces when cutting - a total loss can result! Marc will cut a few samples with local cutters just to see if the material is stable. Here I am checking to see if the Parti Colored Tourmaline from the Lundazi tourmaline deposit is stable - it is! The cutting standards in Africa are of low standards, meaning that the cutters only cut the gems to preserve weight and not to maximize their beauty.  
 

A Brazilian gem cutter that Marc employs, at work on a Tanzanite. The Brazilian cutters employ what is called the "gem peg" method which they adopted from the German cutters long ago. They have customized this method to perfection. In this picture you can see how the gemstone is attached to a special stick by doping wax and then placed onto a diamond impregnated spinning lap with the other end placed into guide holes drilled into a piece of wood. The placement into the guide holes is all done by hand and eyes with a special "touch" that only comes from many years of experience. Less expensive materials and small stones of less than one carat are sent to China or Thailand for cutting.

 Cutting Tanzanite



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