Tanzanite
A splendid clear stone. It
is mainly blue, but parts of the stone will also look violet.
Treatments before purchase
Almost all tanzanite is heat-treated, when first mined
it's a muddy brown colour. The treatment is permanent.
Only a few
pieces need no treatment, these are even more attractive if you are ever lucky
enough to see one (I never have).
Inclusions and fractures are rare, so fracture filling is
very unlikely. However we have seen reports that some colour enhanced stones are
appearing. As yet there is insufficient information to give any further
guidance.
It's not a treatment, but you must be aware that
some stores are selling tanzanite coloured CZ, so read descriptions
carefully. If the stone's name is
not spelt exactly as shown here,
it's almost certain to be a trademark for blue CZ.
Caring for Tanzanite
The stones are comparatively soft, and will be scratched
by household dust. Do not wear when doing manual work (including
housework).
They can be soaked in lukewarm water to clean them, but should
not be soaked in Silver Dip.
Treat with care, and enjoy these beautiful stones for many years. They look splendid,
especially when seen with diamonds, and are
ideal for special occasions.
I checked 3 rings before taking this picture. This gem had the best colour, note how it varies between blue and violet. The golden gleam in one facet is a reflection from the gold mount.
This was the only stone which had any inclusions, which are
quite rare in tanzanite. They are probably growth tubes, and would have
contained liquid as the gemstone formed.
Looking at the picture
the inclusions are very noticeable. In reality they're almost invisible, I
carefully arranged the lighting to highlight them.
Click here
for a larger image (268KB), it will open in a new tab.
Below: Detail of the
inclusions, the best I could achieve with our equipment. The broad rough
line near the top is an edge between facets on the back of the stone, rather out
of focus. The other horizontal and parallel lines are the tube-like inclusions. This stone showed some damage by chipping to facets at the back, not visible to the naked eye.
