Tanzanite Article in brief

Introduction

Picture 1: Rough and Cut and polished tanzanite

Tanzanite was formed over 600 million years ago when Mt. Kilimanjaro erupted caused a unique set of conditions to form deep within the earth - heat and pressure mixed with rare chemicals such as Vanadium to allow this exceptionally rare gem stone to form. These conditions remained constant for the entire 600 million years and Tanzanite grew. It was first discovered by man in 1967 when an enormous grassfire swept the land below Kilimanjaro Mountain.

As Tanzanite is a brownish color in its rough state, the crystals lying on the surface were never noticed until when the grassfire had burnt the land and heated the stones. They turned bright, glittering violet-blue in the sunlight and attracted the attention of some Maasai tribesmen. Tanzanite was named by Tiffany & Company (New York) and for the first ten years after its discovery Tiffany's had the exclusive right to this lovely gem stone. Today, after the liberalization of the Tanzanian economy, it is a free market.

To date the only known reserve of Tanzanite gemstone in the world is a strip of 8km by 1km at Merelani area in Manyara region, Northern of Tanzania on the slopes of the legendary Mt. Kilimanjaro at Merelani Tanzania. To remember this you can imitate Tanzanite Poem by Eng.Gilay Shamika;

Tanzanite the uniqueness of Tanzania,

Only Tanzanite in Tanzania,

Only tanzanite with tantalizing tricolor,

The stones on the foot of Mt.Kilimanjaro,

The stones of 21st Century and

The stones of December birthday.

Geology

Tanzanite is a thousand times rarer than diamonds and is trichroic, which means that in its rough form, it radiates three different colors from each of its crystallographic axes: blue, violet and burgundy. Tanzanites are found in Lelatema Antiform in Merelani, Manyara Region and its chemical formation is: 3Tsavorite + H2O + 5CO2 = 2Tanzanite + 3Quartz + 5Calcite

Tanzanite is found within a relatively complex geological environment and is found in 'chocolate-tablet' boudin structure, typically located in the hinges of isoclinal folds (folds dipping in the same direction) present in the ore body. The Geologists at Tanzanite one has identified two potential strips of these unique zones in the area and has named them as Upper Horizon and Lower Horizon.

Unique features of Tanzanite to prove it’s natural

Tanzanite is the only gemstones in the world that is "trichroic". This means that when white light passes through, it breaks into 2 paths and creates 3 different colors - one axis will look violet, reddish brown and the third a blue-violet. The picture below shows the same Tanzanite crystal from 3 different angles showing its amazing trichroism. This is the confirmation that, the tanzanite you have is natural and not synthetic (manmade).

Picture 2: (Picture Tanzanite into different lights left side under white light and right side under incandescent light

Gemological properties of Tanzanite

Gemological Properties of Tanzanite	Unit of Measure
Gem Species	Zoisite
Specific gravity	3.35
Hardness (Mohs Scale)	6.5
Toughness	Fair
Stability to light	Stable
Carat Weight	Below 1-10 ,rarely 100 +
Birthstone	December

Treatment and grading of tanzanite

Tanzanite when heated at 600 centigrade it changes its color from pale blue/brown to deep blue/brown color. Though sometime in the market the grading includes AAA, AA and A, signifying A,B and C grade, but the grading within the country ( TanzaniteOne) the grading is as seen in the table below.

Colour grading  of  Tanzanite	Explanation
A	Exceptional Colour, Eye Clean
B	Rare Deep Blue/other Colour, Eye Clean
BSI	B Colour-Slightly Included
BI	B Colour Included
BL	B Lighter Colour Grade, Eye Clean
BLSI	B Light-Slightly Included
BLI	B Light Included
D	Opaque Material(agreed to use D instead of O )

Generally all tanzanite with inclusions (embedded with unwanted material outside or inside) that is BSI,BI and BLSI are mostly termed as grade C. From this information, you are now aware of the only source of tanzanite and the properties of tanzanite which will guide you to buy the natural tanzanite.Welcome to the next gemstone next week.