Climbing Kilimanjaro & Tanzania Safari

Zoisite (Variety Tanzanite)
Tanzanite is the important gem variety of zoisite (zoisite is also refered
to as epidote)
Color is variable. Gem varieties are often sapphire blue or violet blue.
However, other colors occur, like the red variety (thulite), and a green
variety.
Hardness: 6.5-7 (note this hardness is less than normally desirable for a
gem used in jewelry subject to abrasion by dirt and dust)
Crystal system: orthorhombic
Composition: Ca-Al-silicate (tanzanite color is attributed to a Vanadium (V)
as an impurity strongly pleochroicView an uncut crystal.

Where is it found?
The variety of zoisite known as tanzanite was discovered in Tanzania in
1967.

TANZANITE  occurs in pegmatite veins (inclusions suggest hydrocarbon-rich fluids) .

WE usually heat treated at 400 - 500 C to remove brown tints,
deepen blue

-Some cats eye varieties due to channels or needles
-Best orientation for color not same for chatoyancy

Clarity is the second most important of the 4 c's when considering Tanzanite
quality. Clarity simply refers to how inclusion-free a gemstone is. Once
again, the most universally accepted and most documented system is the GIA
system but there are also numerous other trade based systems in use. The
basic rule with Tanzanite is that it should be at least eyeclean but
preferably loupeclean too. Top stones are loupeclean. Below is a chart
showing the GIA clarity grading system.

VVS : This is the top grade in the GIA system. Tanzanite is classed by the
GIA as a "Type 1" gem which means it is graded very strictly. Stands for
Very very slightly included and whilst most VVS Tanzanites are flawless they
can contain minute inclusions which are difficult to see with a loupe (10x
magnification) and invisible to the unaided eye. Typical minute inclusions
may be very fine needles, tiny hairline feathers, very faint clouds and
percussion marks.

VS : This stands for Very Slightly Included and these stones are
characterised by minor inclusions which are somewhat easy to see under 10x
magnification but usually invisible to the unaided eye. Typical inclusions
may be small included crystals, liquid inclusions, fine needles, small
feathers

SI1 - SI2 : This stands for Slightly Included and these stones are
characterised by noticeable inclusions which are apparent under 10x
magnification. In SI1 they are usually visible and SI2 quite visible to the
unaided eye. Typical inclusions are included crystals, large liquid
inclusions, feathers, dense clouds.


I1-I2-I3 : The lowest grade. Stands for Imperfect. These stones are
characterised by inclusions that have a negative effect on either
appearance, durability or both. At I1 there is a moderate effect on either
factor, I2 a severe effect on either factor and I3 a severe effect on both
factors.

In terms of Tanzanite, a top stone must be VVS. Any lesser clarity grade
will affect the value downwards and denotes a lower grade stone.

When purchasing Tanzanite there are several factors you need to
consider - these are the 4 c's - Colour, Clarity, Carat Weight and Cut.

COLOUR

Colour is the most important of the 4 C's when considering Tanzanite
quality. It can also be one of the most confusing aspects as you surf the
web as so many different sites use different terms/grading systems and it is
difficult to effectively compare one with another.

COLOUR GRADING SYSTEM.

There is only one universally accepted official grading system for coloured
gems and that is the GIA system (Gemological Institute of America). However,
there are numerous trade based systems as you will see when surfing the web.
The majority of these are very subjective and vary widely. One of the terms
commonly used (and misused) in the trade is AAA Tanzanite. This is a term
used by the miners to denote the very top grade of Tanzanite - the very
deeply saturated exceptional stones.

Below is a suite of Tanzanite loosely representing the colour grades as they
descend. We have used the GIA system but included some of the other trade
grades often used to help with comparison purposes.Of course there are many
other colours which fit in between these but it serves as good basic guide
to colour.

GIA GRADE
bV 6/5 or vB 6/5.

OTHERS
AAA
vB 1+
bV 1+
Exceptional
Vivid Exceptional

GIA GRADE
bV 6/4 or vB 6/4 or bV 5/5 or bV 5/5

OTHERS
A
AA
vB 1
Fine.

GIA GRADE bV 4/4 or G 4/4 or bV 5/3 or vB 5/3

OTHERS
B
vB 2
bV 2
Fancy 1

CONSUMER PROTECTIVE NOTE;



Whilst many sites proclaim to be selling AAA stones from Block D, most are
actually dealing in the A range. Prices are considerably lower for this
material and it has become a marketing ploy to represent lower cost material
as AAA (bV 6/5 vB 6/5) at low prices. True block D AAA material is very rare
and difficult to get. Less than 1% of all Tanzanite production is true AAA
and it is considered exceptional. It is thus at a premium price right from
the mouth of the mine to the very few highly selective and high end jewelers
who have access to it. Beware of sites offering this exceptional material at
prices too good to be true. Chances are you will be buyng a grade to several
grades lower. This is fine as even lower grade Tanzanite is very beautiful,
but it shouldn't be misrepresented as AAA.

CARAT WEIGHT.

Tanzanites exist even in the 100+ carat range but these are rare. Generally
stones are in the below 1 - 10 carat range. Carat weight affects the price
generally as weight increases stones in the same quality bracket will cost
more per carat.

CUT.

Although it has the least impact on value of the 4 C's cut is still
important. In the market, tanzanites are found in a variety of shapes and
cutting styles. Ovals and cushions are the most common, but rounds are also
seen, as are other shapes, including emerald cuts, trillions, etc.
Cabochon-cut tanzanites are not often seen. Cuts should be proportional -
you don't want to pay for a stone with alot of weight in the pavilion for
example when this weight will be invisible in a setting.



OTHER CONSIDERATIONS.

FAKES / SYNTHETICS / IMITATIONS : Tanzanite has never been synthesized, but
a number of imitations exist. The most common is blue-violet glass. A
synthetic fosterite has also been used as an imitation and is known as
Tanzanique in the trade. It has a lower RI than Tanzanite and does not have
the same pleochroism so is easily distinguished from the real thing.
However, laymen can easily be fooled so always buy from a reputable dealer,
preferably a member of the ICA (International Colored Gemstone Association)
which has a strict code of ethics.



ENHANCEMENTS : Virtually all gem tanzanite of a blue violet color has been
heat-treated to enhance the color. In the rough state most Tanzanite is
predominantly brown. Heating at 500 to 600 degrees centigrade causes this
colour to change to blue. This is a permanent and stable change.

LIGHTING : A great deal of Tanzanite marketing makes a big deal of the "red
flash" phenomenon of Tanzanite. This is one of the features of the stone and
is due to Tanzanite's trichroism. Tanzanite is extremely light sensitive,
with incandescent lighting (yellow lighting found in common light bulbs)
tending to shift its color to the violet side causing the red and pink
flashes to appear within the stone. The 2 images below of the same stone
show it under white (daylight) and under incandescent light:

Under white light


Under incandescent light


AFTER KNOWING ALL ABOUT TANZANITE, LET’S TALK ABOUT PURCHASE.

WE WILL TALK ABOUT PURCHASE IN TERMS OF WHERE TO BUY IT, FRAUDLENT AND HOW
TO SHIP IT.

MOST OF PEOPLE IN TANZANIA ARE HONEST, ALTHOUGH THERE SOME RARE CASES OF
FRAUD PRACTISED.THESE FRAUD CASES ARE MAINLY BROUGHT TO TANZANIA BY WESTERN
AFRICA COUNTRIES(SENEGAL, NIGERIA), AND WESTERN COUNTRIES. I HAVE HEARD THAT
TANZANITE IS EVEN MADE IN LABORATORIES. SO IT IS MY ADVICE TO BUY GENUINE
TANZANITE FROM REGISTERED AND LICENSED DEALERS.

IN TANZANITE, BUYING TANZANITE IS SIMPLE AND NO MUCH THREATS OF BUYING FAKE
TANZANITES.

THERE ARE A NUMBER OF TANZANITE DEALERS WHICH MOST OF THEM HAVE MINING
BLOCKS IN MERERANI AREA ARUSHA. THESE CONDUCT TANZANITE MINING, CUT AND SELL
THEMSELVES. THIS IS A BIT BETTER PLACE TO BUY TANZANITES JEWELS.

THE DEALERS ALSO USE SPECIAL METERS TO MEASURE AND RECOGNISE GENUINE
TANZANITE.

FROM THESE DEALERS YOU CAN BUY TANZANITES AT REASONABLE PRICES AND GET
BETTER DEALS.

We also Sell Gold, Gold Jewels and necklaces plus other types of Minerals like Saphire, Ruby e.t.c

WHEN YOU COME TO TANZANIA, CONTACT US.

CONTACT US NOW FOR COMPETITIVE PRICE AND COMFORTABLE TRIP

 

Email; info@kili-tanzanitesafaris.com

 

 

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