| were found in 1998. |
The
existence of gemmiferous minerals, including |
 |
corundum
was known for a long time in the sandstones |
| of
Isalo.
French geologists having undertaken research |
| in
1946
in particular. If their discovery did not cause |
| particular
interest
at that time, several reasons can be |
| advanced :
the
political instability which reigned after |
| the
second world
war in the colony, and the fact that |
| the majority
of
corundums coming from the Ilakaka |
|
area
must be
heated
to be marketed, indeed, |
| a blue stone, but cloudy,
could
not inevitably let |
| suppose to its discoverers that it
would
become pure |
| and transparent after a suitable heat
treatment. |
| Moreover, knowledge in this field remained |
| summary
at that time. In Ilakaka, the arrival of |
| merchants
coming from Thailand and from
Sri-Lanka |
| changed things,
because
this group of purchasers |
| |
became experts in "the
enhancement
of corundum. |
|
" Tsy misy mandronono, tsy misy prix" |
" Thus, the cloudy stones of
the best
quality will often |
|
This sentence is none by everyone in |
be sold as (untreated
Sri-Lankan sapphires) |
|
Ilakaka.
|
on the international market, this because of
the |
|
That means that : " if the stone is not milky, |
difficulties in detecting heating treatment in a stone |
|
its owner will generally not obtain the best price |
from
Ilakaka containing a haze
of tiny titanium |
|
from it." |
inclusions
only, reabsorbed after heating. |
|
(
Note: that true untreated Sri-Lankan sapphires are |
|
rare.) |
|
|
|
|
 |
|
|
|
Ilakaka river,
where the exploitation of the first sapphires began in 1998. |
|
|
|
|
|
