TANZANITE (ZOISITE) - UNHEATED

This is a well cut stone that was cut in Tanzania by experienced cutters ready to be set in jewellery. It is a natural stone that has not been heat treated. These stones come from a lower mining level and have had some natural heating, causing multi colours in some stones.

Ideal for re seller or jeweller

Natural multi colours

Mohs scale 6.5 to 7

Grading VVS

Weight of stone 0.65 cts app 

size of stone 7 x 5 mm app 

We have some rough Tanzanite specimens in our sister stores QUALITY ROUGH and MINERAL GEM WORLD where you can see how hard it is to cut clean stones like this out of rough.

COLOUR & GRADING SYSTEMS:
Colour is of course the most important of the 4 C’s when determining the quality of a Tanzanite stone. However, it can also prove very confusing when comparing the stones of one Tanzanite dealer compared to the next, especially if you are looking on the internet, since the differing terminology coupled with often confusing grading systems makes comparison virtually impossible.
As we have already seen there are a multitude of Tanzanite grading systems in use but it should be noted that as yet there is no universally accepted method of grading the stone. Even the world's most recognised laboratories have yet to reach consensus on terms used for grading Tanzanite although the

Tanzanite is an extraordinary gemstone. It occurs in only one place worldwide -Tanzair africa. Its blue, surrounded by a fine hint of purple, is a wonderful colour. Thanks to its unusual aura and the help of the New York jeweller's Tiffany, it has rapidly become one of the most coveted gemstones in the world.

Tanzanite is a blue variety of the gemstone zoisite. It consists of calcium aluminium silicate and is not particularly hard, having a value of 6.5 to 7 on the Mohs scale. For that reason, it should always be worn carefully and never placed in an ultrasonic bath for cleaning or brought into contact with acids.

The deep blue of the tanzanite is fantastic, and runs from ultramarine blue to light violet-blue. The most coveted colour is a blue surrounded by a delicate hint of purple, which has a particularly wonderful effect in sizes of over 10 carats. The well developed polychromaticity of the tanzanite is typical: depending on the angle from which you look at it, the stone may appear blue, purple or brownish-yellow. Having said that, most raw crystals are somewhat spoiled by a brownish-yellow component, though it can be made to disappear by the cutter if he heats the stone carefully in an oven to approximately 500°. During the procedure he must pay careful attention to the moment at which the colour turns to blue. This burning is a method of treatment which is regarded as customary in the trade, but the raw stones must be as free of inclusions as possible, since otherwise fissures may occur. In fact working with tanzanite can sometimes give even the most experienced cutter a bit of a headache, the cleavage of this gemstone being very pronounced in one direction. This exclusive gemstone is cut in every imaginable shape from the classical round shape to a number of imaginative designer cuts.