In our newsletter this month:
It's a fact of life in the gemstone industry that many gems are enhanced or treated. The most common form of treatment is heat treatment, which is applied routinely to ruby and sapphire, and to other gems such as tanzanite, blue zircon and blue apatite. Some gems, such as blue topaz, are irradiated to produce their distinctive color; in fact it's virtually impossible to buy a blue topaz which has not been irradiated. Other gems, such as emerald, are treated with oil or resin to fill fractures. More recently, we've seen heat treatment with beryllium diffusion for yellow and orange sapphire, and fracture-filling with lead glass for African ruby. Sometimes it seems like the gemstone world is awash in gem treatments.
If you have the impression that these days almost all gems are treated, please think again. Of our current inventory at GemSelect (over 9,000 gems) about 75% are completely untreated. Most types of gemstones are not treated, and that includes a number of gemstone varieties with excellent hardness and brillance, such as spinel, all the types of garnet, tourmaline, peridot and orange, brown and rose zircon.
While the vast majority of sapphires are heat treated, it is still possible to find completely untreated sapphire gems. They are rare and relatively expensive, but we have recently found a new source and have been adding more of them to our stock. Most of the unheated sapphire gems we've been buying are from Tanzania, long a famous source for tanzanite and tsavorite garnet. We have also found some unheated sapphire gems from Madagascar, Australia and Thailand.
We have acquired unheated Tanzanian sapphire in pink, violet and violet-blue, including some stunning color change pieces. Some of the unheated blue sapphires from Madagascar and Australia are found in large sizes (weighing over 2 carats) and display a velvety texture from rutile silk inclusions that you will only find in unheated sapphires, since the rutile tends to melt when sapphire is heat-treated. We've taken a number of our unheated sapphires to gemological labs for testing, and are confident that all are unheated. If you would like a gemological certificate, just check add gem certificate when you purchase your sapphire and we'll obtain a certificate for you.
To date, tanzanite has been found only in one location in Tanzania. Not only is it rare, but also the industry faces the unhappy prospect that eventually the mines will be worked out. The market demand for tanzanite is so great that prices have been driven higher and higher, and even second rate pieces sell at prices comparable to fine sapphire. So finding a really outstanding tanzanite in a large size can be very difficult. This 10.76 carat piece is the finest tanzanite we've had in our inventory. The color is a rich violet-blue and it has a nicely executed cushion cut. Its clarity is excellent and the gem has been graded VVS.
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Best wishes for the holiday season,
Your friends at GemSelect
- First Published: January-01-2009
- Last Updated: October-27-2014
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