Tanzanite - Tantalizing Gem

Value Considerations

Color

Color Is The Most Important Factor In Determining a Tanzanite's Value.

Tanzanite is characterized by beautifully rich purple-blue colors. It frequently displays a deep intensity that is found nowhere else in the gemstone kingdom. Attractive eye-catching red flashes of fire (from a "trichroic" light property unique to Tanzanite), often augments tanzanite's spectacular color. As in the case of  most other colored gemstones, the richer the color of the gem, the more desirable it is.

Depending upon how they are oriented during cutting, Tanzanite can be pure blue or include the secondary and tertiary colors of the Lavender and purplish tones. Some people prefer the pure blue Tanzanites which most nearly resemble sapphire. Others are called by the violetish blue colors of Tanzanite, feeling they heighten the stone's exotic allure. Obviously, which color you prefer depends to some extent on your personal preference.

In general, tanzanite stones showing more blue are valued higher than those showing more violet. Gradually appreciation for the more violetish tones has risen. Medium dark colors are more desired.

Carat Weight

Like most other gems, when the carat weight of a tanzanite increases, its price per carat goes up. But the premium for larger stones may not be as steep as those found in sapphire and ruby.

Inclusions/Clarity

As in other gemstones, you pay a premium for high clarity gemstones. It is getting increasingly difficult to find large gems of high quality with a good color as collectors are snapping them up. This means the prices is continually going up restricted by supply. Compared to ruby and sapphire, tanzanites can be found in top qualities. Look for gemstones with good clarity that will enhance sparkle, brilliance and ultimately beauty of this gemstone. Try to buy the best quality you can afford.

Shape & Cut

Tanzanites are offered in a variety of shapes and cutting styles. Ovals and cushions are most frequently seen, but round, emerald and trilliant cuts are also common. Slight premiums are levied upon round tanzanites to compensate for the weight loss on cutting. Discounts are frequently given for pear and marquise cuts.

A well-cut tanzanite is symmetrical and shows good polish; facets should be aligned straight in relation to each other, and the girdle; polish conditions should be mirror like with no visible flaws, pits or polishing lines.

Cabochons are not so common in case of tanzanite.

As is the case with other gemstones, size and clarity influences the price of tanzanite gemstones substantially. Collectors bid up the value for greens and the ultra-rare cat's eye stones.

Location/Origin

The world's most predominant source of tanzanite is the Merelani deposit in Tanzania, East Africa. Located in the Rift Valley close by to Mount Kilimanjiro, the mines barely cover 20 square kilometers. With such limited deposits, it is likely that tanzanite can only become more valuable in the future.

Out of the individual deposits at Merelani, a subsection known as "D Block " has earned the reputation for producing the very best "AAA" quality tanzanites. These tanzanites are characterized by intensely deep purple colors with glistening flashes of red.

The Use Of Heat

Virtually all tanzanite is heated to about 500°C in order convert its unsightly brownish coloration to a more appealing blue. Most tanzanites seen on the market today have been subjected to heat treatment. One gemologist said it this way, "If someone is offering you tanzanite claiming that it is not heated, run away from him."

Other Factors

Recent disastrous weather conditions, government embargos and continuing political tensions have restricted the supply, especially of larger fine colored stones. There is also talk of a cartel hoarding high quality stones. Supply had been dwindling while the appetite for this stone had been continually on the rise. The result. Prices keep going up. Tanzanite could turn out to be a great investment if you invest on quality gemstones.

Healing/Metaphysical Properties of Tanzanite

See: Therapeutic Properties of Tanzanite

Identification of Tanzanite

Gemological Data for Tanzanite

Other name: Zoisite
Makeup: Calcium, aluminum, hydroxysilicate: Ca2Al3(SiO4)3OH
Luster: Vitreous
Color Purple-blue
Hardness 6-1/2 - 7
Specific Gravity 3.35
Refractive Index 1.691-1.700
Crystal structure: Orthorhombic
Fracture: concoidal to uneven
Cleavage: 1, perfect
Density: 3.35
RI: 1.69
Pleiochroism: Trichroic, blue, red-violet, yellow-green
Birefringence: .010

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See Also:

Products with Tanzanite

Therapeutic Properties of Tanzanite

Gemstone Infocenter Home

Gift Selections incorporating Gemstones

Guide to Caring for Gemstones

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