Topaz
is a mineral which has been known and prized since biblical times for
its remarkable clearness and transparency. Its decline in popularity
some time ago was due mainly to the fact that many far inferior stones
were wrongly termed topaz. The real topaz is now, however, being more
and more appreciated.
The
real topaz is a silicate of aluminum and is remarkably heavy, and is
also quite hard, being No. 8. The usual color of the gem is yellow, but
topaz are also found in many other shades. As is the case with
aquamarine, the color may often be altered by artificial means. The
yellow topaz of Brazil may, for example, be changed to a pale rose pink
by heating, and this is often done. The heating and cooling of the gem
must be done very carefully and slowly, but the operation presents no
difficulty to an expert, and the pink color when once secured is
absolutely permanent. Crystals of the topaz mineral often grow to
large size, and occasionally specimens of sufficient clearness to be
used as
