Rubies
and sapphires are both members of
the corundum family with the same
hexagonal crystallographic structure.
The basic chemical formula is AL2O3
.. the same for both ruby and sapphire.
It is the presence of chromium,
iron, vanadium and titanium which
are responsible for the wide range
of colors in which the mineral occurs.
The red color in rubies is primarily
a result of the presence of chromium.
A red corundum is known as ruby
and any other color is called a
sapphire.
The
heating of rubies and sapphires
is a widely used and accepted enhancement
process which can improve the transparency
and/or the color of the stones.
The treatment is permanent and heated
stones do not require special care.