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Although
pink and reddish orange colour known as imperial are the
most valuable colours of topaz, this gemstone variety is now
most often seen on the market in a blue colour, thanks to a
new irradiation enhancement process for colourless topaz
developed in the 1970s.
History and Lore
Ancient
Egyptians said that topaz was coloured with the golden glow
of th e might sun God Ra, giving it the power to protect the
faithful against harm.
Wear Topaz
only if you wish to clear-sighted: legend has it that it
dispels all enhancement and helps improve eyesight.
The
ancient Greeks believed that topaz had the power to increase
strength and make its wearer invisible.
Topaz was
said to change colour in the presence of poisoned food or
drink. Its mystical curative powers waxed and waned with the
phases of the moon : it was said to cure insomnia, asthma
and hemorrhages.
The
world’s most famous topaz, the huge Braganza set in the
Portugese Crown, was originally thought to be a diamond.
Topaz is
the traditional US birthstone for November. Blue topaz is
considered an alternate US birthstone for December.
Quality, Value and availability
Topaz can
be amber gold of fine cognac or the blush of a peach and all
the beautiful warm browns and oranges in between.
The most
valuable topaz is more red than yellow : from pale pink to a
“sherry” red. Imperial topaz is also highly valued. Yellow
to brown topaz is more affordable.
The strong
icy-blue colour of blue topaz is created by exposing
colourless topaz to irradiation and heat. Lighter colours
are created by electrons and the darker blue known as London
or Super blue is created by neutrons. Blue topaz is among
the most affordable coloured gemstones.
Topaz is
most often found in a scissors cut, a rectangular gem cut
with curved sides that has triangular facets. Ovals,
cushions and emerald cuts are also available.
Because
blue topaz is readily available and affordable, it can be
found in a wide variety of shapes and sizes, including
unusual cuts.
Sources
Topaz is
mined in Brazil, which is the source of the most sunset-coloured
Imperial topaz, Pakistan and Russia produce beautiful
delicate pink topaz.
The
colourless topaz used to make blue topaz is also mined in
Sri Lanka, Nigeria and China.
Routine Enhancements
The strong
icy colour of topaz is created by exposing colourless topaz
to irradiation and heat. Lighter colours are created by
electrons and the darker blue known as London or Super blue
is created by neutrons. All commercially available blue
topaz is treated.
Heat
treatment is sometimes used to change yellowish topaz to
pink.
Surface
coatings and diffusion treatment can be used to create other
colours.
Care and Cleaning
Topaz has
a high hardness of 8 on the Mohs scale, but it isn’t tough.
Like diamond, it has a pronounced cleavage: a single blow
can break it in half so it should be protected from knocks.
The
treated colour of blue topaz is stable and permanent and
does not require special care.
Clean
topaz with mild dish soap in warm water: use a tooth brush
to scrub behind the stone where dust can collect |
