What is a Natural Sapphire?
Natural, Round Pink Sapphire Gemstone from Tanzania
All of us who love gemstones want to own natural stones. Though high-quality synthetics exist for many gems such as sapphire and ruby, interest in the synthetics is low, despite the fact that synthetic corundum is chemically identical to natural ruby and sapphire.
What about the case of sapphire that forms naturally in the ground, but is then later enhanced by humans using techniques common in the gem trade? Are these sapphires natural? Many gem dealers and jewelers would say yes. Others would disagree and contend that only an untreated sapphire is truly 'natural'. Yet others would say that certain treatments are acceptable, but others are not. So where do we draw the line? Here is the opinion of one dealer who trades high value sapphire:
Let's see if we can make sense of this recommendation. First the writer argues that "extreme heating" is not acceptable, then he goes on to suggest that a gem is not natural "if humans have a hand in creating the beauty through heating and processing". The writer is worried that there is a "slippery slope" that we'll slide down if we accept any kind of treatment at all. It seems to be a good point - if you accept one kind of treatment, why reject another?
Should we say then that any processing of the raw material is acceptable if it simply brings out the properties of the natural gemstone? That would allow heat treatment, since applying heat to sapphire changes the color and/or clarity because of the chemical composition of the gemstone. Indeed it is often argued that heat treatment is similar to a process that occurs naturally in the earth when the sapphire is formed as a result of heat and pressure.
But as the well-known corundum expert, Richard Hughes, has argued, "ordinary heating diffuses aluminum vacancies and hydrogen in and out; the surface diffusion process works in the same way, but with heavier elements (Ti, Fe, etc.)". Once any kind of treatment is introduced, complex chemical reactions are created in the gem material.
The most important thing for the buyer is to understand the different enhancements that are used on gemstones, and understand how these affect price. Since each new kind of gem treatment is a way of enhancing previously unsaleable material, it is constantly expanding (or at least maintaining) the supply of scarce gemstones in the market. Without these treatments the supply of many gemstones would be so scarce that this article would probably be more about synthetics rather than 'natural' gemstones. |
- نشرت لأول مرة: ديسمبر-12-2007
- آخر تحديث: يناير-24-2019
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