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Learn About Gems
Tanzanite
Did you know tanzanite is one of the most popular and desirable gemstones today? People are captivated with the beauty and color of tanzanite. Consumers are always willing to purchase gemstone jewelry with tanzanite. Recently, the International Colored Gemstone Association selected tanzanite as December's birthstone. It will join turquoise and zircon in that honor. This is welcome news because tanzanite is the most popular gemstone after blue sapphire. Quite an achievement for a gem that was unheard of until discovered in the 1960's in Tanzania. In addition, tanzanite is also the suggested gemstone for a gift when celebrating a 24th wedding anniversary.
Tanzanite comes in various shades of violet-blue. The less expensive colors range toward violet, a light purplish blue. The top colors are deep blue with a hint of violet-a velvety soft color that is highly desirable. Of course all colors are popular with the public and are therefore very much in demand. Although tanzanite is blue, it is not a substitute for sapphire. It is not as hard as sapphire and may become abraded when worn in a ring that exposes parts of the gem. Tanzanite is about the same hardness as opal and should be treated with special care. Because of its relative softness, tanzanite is more trouble free in shapes such as cushion, oval, and round. Tanzanite in shapes such as marquise, pear shape, and radiant will be testing the bench jeweler's stone setting skill. The important thing to remember about tanzanite is that it does not like surprises! It is especially susceptible to sudden and/or extreme temperature changes. Do not steam clean a piece of jewelry with a tanzanite in it. Do not put it in an ultrasonic cleaner. Tanzanite should be removed from the jewelry before working on it. Jewelry should be cleaned thoroughly and then re-set the tanzanite. Tanzanite jewelry items should be cleaned gently.Usually it is best to set tanzanite in jewelry that protects it from possible scratches and chips by having the mounting or ring handle the blows rather than the gem. You should also be mindful of tanzanite's sensitivity to temperature extremes. One should not wear such jewelry when in the kitchen where it is possible to go from freezer to hot oven during food preparation.
To improve the color, all tanzanite is heat treated to approximately 750-930 degrees Fahrenheit. The color will remain stable unless subjected to the jeweler's torch. Additional heating will not improve or deepen the color. I have found that consumers love all of the possible variations of tanzanite color. The lighter shades look good with peridot as accent stones. The darker and deeper blue shades look great with emerald accents. Prices for tanzanite have been on a roller coaster ride this past year as a result of allegations of a money-laundering conduit for terrorists. This theory has been disproved by the U.S. State Department and now prices are firmer. Expect to pay in the $600 per carat range for lighter colored material and up to as much as $1,500 per carat for top quality tanzanite. Tanzanite is usually found inclusion free and in a variety of shapes and carat sizes. However, the first attribute of a gemstone is its color so judge the color first and not clarity. Then evaluate the clarity and then the cut or make of the gem to determine if the gemstone is right for you and your pocketbook! Lastly, tanzanite is very popular with "cruise line" vacationers. Cruise line patrons shop at exotic ports-of-call and are lured into emotional purchases, which are further enhanced by the "no tax" purchase. However, in my opinion tanzanite sold at the majority of these locations is usually over priced for the quality offered. The quality of the gem and the manufacturing of the finished product may be somewhat questionable. Always be aware of inferior quality jewelry when shopping abroad. After all, it isn't very likely or practical for one to return a piece of jewelry purchased on a cruise hundreds or even thousands of miles away.
TREATMENT: Frequently heat treated
MOHS HARDNESS: 6 - 7 (a very soft stone)
CHEMICAL COMPOSITION: Hydrated calcium aluminum silicate
REFRACTIVE INDEX: 1.69 - 1.70 (The angle light is bent traveling through a gemstone)
DENSITY (SPECIFIC GRAVITY): 3.35 (The number of times heavier a gemstone is compared to water)
PRINCIPLE SOURCES: Tanzania
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