Traditionally, the most favored color
for Sapphire is the rich and
soft "cornflower blue" seen
in Kashmir stones. Though there
is virtually no mining in Kashmir
now, sapphires that approach
this color are found in Sri Lanka.
Some of the sapphires that are
mined and polished in Sri Lanka
are not heated. The photograph
on the next
page shows an untreated
Sri Lankan sapphire. It is transparent
with a somewhat velvety appearance,
giving it a unique character.
A tone level of 5 makes it very
attractive even under weak lighting.
Darker stones with tone levels
of 6 or 7 exhibit a unique and
rare beauty under stone lighting,
but do not appear as beautiful
under weak light. The sapphire
in the ring below is also untreated.
It has a somewhat light tone
of 4, but shines beautifully
even from a distance. As with
Sri Lanka, there are sapphires
from Myanmar and Kashmir that
are not heat-treated.
Crystals
that have a beautiful color in
their natural state do not require
any processing beyond polishing.
In general, however, most sapphire
crystals are not transparent,
or they are too dark or too light.
These crystals have their transparency
and tone of color adjusted through
heating at temperatures ranging
from several hundred to nearly
two thousand degrees Celsius. |
Around
1977, it was discovered that the
near-colorless Sri Lankan sapphire
rough called "geuda," which
had been routinely discarded until
then, would become a gorgeous blue
color when heat-treated. Large quantities
of this rough material were taken
to Thailand, where they were heated
and polished. From there they were
introduced to the world market, where
they have succeeded in capturing
the largest share. Though their beauty
achieved widespread recognition,
deals of their heat treatment have
not reached the general public.
There
are subtle difference between the
liveliness of a naturally beautiful
color and that of a beautiful color
brought about through heat treatment.
And individual's preference is a
personal decision, but one that should
be made with the knowledge of whether
the beauty is natural or a result
of treatment.
Sapphires from Tanzania
and Madagascar began appearing on
the market in the 1990s, and some
of these show a fine quality similar
to Sri Lankan sapphire. Most large
sapphires, however, are from Sri
Lanka. |
