This remarkably popular gem was discovered during the late 1960’s in Tanzania’s Great Rift Valley. A relative newcomer to the gem and jewelry scene, the last 30 years has seen tanzanite establish itself with great success becoming America’s #1 selling gem after blue sapphire.
While arguably the easiest to assess of all the precious gems, understanding where value lies in tanzanite still requires some basic knowledge of this gem species. All the standard gem-value measurements are applied, but it must be remembered that prevalent tendencies of this richly colored gem for large sizes and high clarities do affect their pricing structure.
Color Impacts Tanzanite’s Value
Popularized by beautifully rich purple-blue colors, tanzanite frequently displays a deep intensity that is found nowhere else in the gemstone kingdom. Attractive eye-catching red flashes of fire (a “trichroic” light property unparalleled by other gems), often augments tanzanite’s spectacular color. As with most other colored gemstones, the richer the color of the specimen, the more desirable it is.
Although traditionally thought of as an intensely purple-blue gemstone, tanzanite also occurs in a variety of other colors such as pink, green, ultramarine and a steely kind of blue. Frequently these tanzanites exhibit a color change from the more bluish hues under daylight, to pinkish violets under incandescent light.
Carat Weight of Tanzanite Impacts Per Carat Prices
Tanzanite frequently occurs in large crystal sizes and such specimens can be thought of as being fairly accessible. These large sizes also help to enhance tanzanite’s perceived depth and richness of color.
Similar to most other gems, when the carat weight of a Tanzanite increases, so does the price per carat. However, large tanzanite crystals with their abundant occurrence rates are simply more plentiful than ruby and sapphire. This means that weight related price jumps in Tanzanite are far less severe than in ruby and sapphire. Indeed, it is not uncommon for comparable quality 3 Carat, 4 Carat, and 6 Carat tanzanites all to have the same or very similar per carat prices – something that is unthinkable for ruby and sapphire.
Freedom From Inclusions
Large, gem quality clean tanzanite crystals are relatively common when compared to other precious gems. Well known for their predisposition for virtually flawless clarities, this tendency enhances sparkle, brilliance and ultimately beauty. While it would be incorrect to say tanzanite is a clean gem species, with so many near flawless tanzanites available on the market, obtaining such top quality clarities is within everyone’s grasp – something that cannot be said of sapphire, sapphire or emerald.
Shape & Cut
Tanzanites are found in a variety of shapes and cutting styles. Ovals and cushions are most frequently seen, but round, emerald and trilliant cuts are also not uncommon. Like many other gems, slight premiums are levied upon round tanzanites due to the higher loss of costly crystal rough during cutting. Conversely, 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.
Unlike ruby, sapphire and emerald, cabochons are infrequently seen in tanzanite. This serves as a reminder of tanzanite’s predisposition for high clarities.
Sources Of Tanzanite
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 and kudos for producing the very best “AAA” quality tanzanites. While characterized by intensely deep purple colors with glistening flashes of red, tanzanite from the other locales such as “C Block”, can be in reality produce gems as every bit as fine.
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, an age-old practice thought to have originated in Sri Lanka some 2,000 years ago. Without this practice, virtually no tanzanite at all would be seen on the market today.