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 January 2009
In our newsletter this month:
Unheated Sapphire
New and Interesting Gemstones
Rare and Unusual Gems
Customer Questions
Unheated Sapphire
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 oils or resins to fill fractures. More recently, we've seen heat treatment with beryllium diffusion for yellow and orange sapphires, and fracture-filling with lead glass for African rubies. Sometimes it seems like the gem world is awash in gem treatments.
But 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 in the market. 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 we're finding are from Tanzania, long a famous source for tanzanite and tsavorite garnet. But we are also finding some unheated sapphire from Madagascar, Australia and Thailand.
We've found 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 larger sizes (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.
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| New and Interesting Gems -- updated November 9th |
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Watermelon Tourmaline from Nigeria: Watermelon tourmaline is one of the most distinctive gems in the world. We have just purchased a small number of exquisite pieces from Nigerian with outstanding color and clarity. These are the finest we've seen this year. |
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Boulder Opal from Australia: Boulder Opal is the second most prized form of opal, after black opal. The name derives from the fact that this opal is found embedded in ironstone boulders. Boulder opal is especially attractive because, like the black opal, it has a dark body tone which adds vibrancy to the play of color. We've just purchased a small lot of excellent pieces, in sizes between 4 and 15 carats. |
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Clinohumite from Tanzania: Clinohumite is a rare mineral. It is a member of the humite group of minerals, which includes humite, clinohumite, chondrodite, and norbergite. Only three sources of gem-quality clinohumite are known: the Pamir Mountains of Tajikistan, the Taymyr region of northern Siberia and the Mahenge plateau of Tanzania. Usually clinohumite is found in sizes under 1 carat but we just have acquired a small number of new pieces from Tajikistan in the 2-3 carat size. |
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Huge Topaz from Brazil: Gem-quality minerals are sometimes found in exceptionally large sizes. We've acquired some natural topaz from Brazil in sizes between 360 and 507 carats. We currently have 4 pieces in a light champagne color with outstanding clarity (all of been graded IF). Collectors take note. |
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Fluorite from Namibia: Fluorite is said to be the most colorful mineral in the world. We've just bought a new stock of some very colorful pieces, including electric greens and blues and some fascinating multicolor pieces. Most of the new pieces are in the 10 to 45 carat size, with a few larger stones, all with excellent clarity. We've recently added some very colorful cabochons as well. |
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Color-Change Diaspore from Turkey: Diaspore, sometimes marketed under the name Zultanite, is a color change gem from Turkey recently introduced to the international market. Under natural or fluorescent light, Diapsore has a kiwi green color, with flashes of yellow. Diaspore displays a champagne color under incandescent lighting, and when exposed to subdued lighting, such as candlelight, has a pinkish hue. We've recently bought a substantial number of new pieces, with a good choice of cuts and sizes. |
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Snowflake Obsidian from Mexico: Obsidian is a naturally occurring volcanic glass. It is formed when felsic lava extruded from a volcano cools without crystal growth.In some stones, the inclusion of small, white, radially clustered crystals of cristobalite in the black glass produce a blotchy or snowflake pattern, and this is known in the gem trade as snowflake obsidian. |
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Unheated Sapphire from Tanzania, Madagascar and Thailand: Our unheated sapphires have been very popular and we continue to increase our stock (now over 700 pieces). For the discriminating gem buyer who will accept nothing less than 100% natural, you'll find pink, blue, green, yellow and violet pieces, all guaranteed to be unheated. You may be surprised how affordable these are in the smaller sizes. |
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Seraphinite from Russia: Seraphinite is a trade name for a particular form of clinochlore, a member of the chlorite group. The dark green color of seraphinite is enhanced by a silvery and feathery shimmer caused by mica inclusions. Seraphinite was named for the seraphim, the highest order of angels, because of the feather-like appearance of the chatoyant fibers in the stone. This fascinating gemstone is a new addition our inventory. |
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Top Grade Amethyst from Brazil: We've just acquired some top grade natural amethyst from Brazil in very large sizes, ranging from about 20 to 75 carats. These are all VVS or IF clarity in the richest purple we've seen in amethyst in a long time. If you've been looking for a very special piece of amethyst, you'll want to check these out. |
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Demantoid Garnet from Namibia: Demantoid is the rarest and most valuable of the garnets, and is one of the most difficult to find of all colored gems. It is one of the few colored gemstones with a luster and brilliance similar to diamond. We have built up a stock of more than 100 pieces of Namibian demantoid, including some very fine matched pairs. |
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Amber from Poland: Amber is the fossilized hardened resin of the pine tree, Pinus succinifera, formed mainly in the Eocene epoch of the Tertiary period, about 50 million years ago. Amber has been used since prehistoric times for jewelry, amulets and religious objects. The most prized pieces contain inclusions of insects or plants or pyrites. Most amber is found in the Baltic region. We buy amber just a few times a year from our source in Poland and we've just added a new stock. |
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Turquoise from Afghanistan: Turquoise has been known and valued for thousands of years. We've bought some new pieces from Afghanistan, in an interesting variety of blue and blue-green hues. We've also found some of the popular apple-green turquoise that we first carried last year, and some superb matched pairs in blue. |
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Huge Star Rose Quartz from South Africa: We carry many large gemstones, but none as large as these Star Rose Quartz. We've collected 9 pieces over 100 carats, with the largest weighing in at an amazing 974 carats. The star effect in rose quartz is unusual in any size, but quite rare in these very large stones. |
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Axinite from Tanzania: Axinite is a group of brown to violet-brown or reddish brown minerals that sometimes occur in gem quality. Axinite is distinctive for its strong vitreous luster when polished, and its interesting pyro- and piezo-electric properties. Axinite is also popular with mineral collectors due to its unusual crystal structure. We have found a small stock of golden brown Axinite from Tanzania. |
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Spinel from Burma: We buy fine spinel whenever we can find it, and we've recently added some very fine pieces of Burmese spinel. You'll find red, violet, orange, blue and gray in a variety of shapes and sizes, including a good selection of pairs and lots. |
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Blue Sapphire from Madagascar, Ceylon and Tanzania: One of the most classic of all colored gemstones, the blue sapphire is always fashionable. This brilliant and hard-wearing gemstone is perfect for any kind of jewelry. We've added many new stones to our stock of more than 400 blue sapphires, including a number of excellent cornflower blue pieces. |
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Jadeite from Burma: Jade has been known and treasured for more than 7,000 years. But only in 1863 was it discovered that jade is actually not a single mineral. What was traditionally called jade is in fact two separate and distinct minerals: jadeite and nephrite. Jadeite is the rarer and more valuable jade, with the most famous deposits coming from Burma. We have verified samples of our Jadeite at the AIGS gemological lab in Bangkok. You'll find a good range of colors in these, including white, green and lavender. |
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Spessartite Garnet from Mozambique: We have added a large number of new pieces to our extensive inventory of this very popular gem. We now have over 500 pieces in stock, in mandarin and red-orange, in both cabochon and faceted. The range of sizes and quality grades is extensive. Our most recent additions are in the best mandarin orange color, mainly in smaller sizes. |
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Color-Change Garnet from Tanzania and Madagascar: We've recently found some rare Color-Change Garnet from Tanzania with a dramatic color change from greenish-brown to red pink. We have a small number of pieces, mostly eye-clean, in the 1 to 2 carat size. We've added these to our substantial stock of Color-Change Garnet from Madagascar. |
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Sphene from Sri Lanka: We have added some excellent new pieces to our stock of this rare gemstone famous for its remarkable dispersion or fire. These are bright golden and green pieces in interesting shapes and cuts, including a number of rounds in smaller sizes. Sphene tends to have inclusions, but we've found a number of eye-clean pieces. |
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Emerald from Colombia: We have just received a new stock of Colombian emeralds with rich color and good transparency. These are mainly ovals and pears in smaller sizes, ideal for earrings and ring settings. |
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Rare and Unusual Gems
Each month we feature a rare and unusual gem from our inventory. This month we feature an exceptional large tanzanite from Tanzania. 
To date tanzanite has been found only in one location in Tanzania. Not only is it rare, but the industry faces the unhappy prospect that eventually the mines will we worked out and no more tanzanite may be found. 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 ct piece is the finest tanzanite we've had in our inventory. The color is a rich violet blue in a nicely executed cushion cut. Clarity is excellent with the gem graded VVS.
Customer Questions
Every month we answer questions of general interest from our customers. Please feel free to send your questions to help@gemselect.com. |
| Q: |
How do I determine that a sapphire has not been heated? What do I look for? Your advice is appreciated, MRJ, UK |
| A: |
Determining conclusively that a sapphire has not been heat-treated is something that only a very experienced gemologist can do. Gemologists examine internal structures under high magnification and look for the presence of crystal structures that would be altered by heat treatment, since many charactertistic inclusions such as rutile and zircon crystals have a lower melting point than corundum. Some laboratories also use high tech tools such as Raman spectroscopy and laser tomography. |
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Can you certify country of origin in your gem certificates? KJ, USA |
| A: |
We currently offer identification reports from independent gemological labs that do not certify country of origin. However, there is growing interest in certifying gemstone origin and a number of labs have done (or are doing) research to enable them to do that. Just be aware that the results are not always conclusive, and most labs offer their identification as a "considered opinion" only. For more information on the issue please see our recent article on Country of Origin.
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| A final note -- If you send us email, please be assured that we answer all our email very promptly, 6 days a week. But we sometimes have problems with spam filters on the receiving end, so please adjust the settings on your mail client so you can receive mail from help@gemselect.com.
Best wishes for the holiday season,
Your friends at GemSelect |
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