Topaz - How to Identify?By:Ardamun
Summary: Citrine is mostly, and erroneously, called topaz, though both are two distinct species. Citrine is quartz, and is much lighter than topaz, which is Hydroxyl Fluorosilicate of Aluminum.
How To Identify Different Topaz?Topaz is the hardest silicate mineral and one of the hardest minerals in
nature, and a very popular gemstone for jewelry. In the ancient past, topaz
was always associated with the yellow color, and all yellow and golden-hued
gems were called topaz. Fine topaz normally occurs as a colorless crystal,
though other colors, such as pink, blue, green, 'sherry', brown, etc are
known to occur as well. You will find a variety of yellow gems wrongly being
sold as topaz, such as:
* Smoky topaz - which is actually smoky quartz
* Citrine topaz - which is citrine
* Madeira topaz - a citrine quartz
* Bohemian topaz - which is also citrine
* Occidental topaz - is also citrine
* Oriental topaz - which is yellow corundum
image courtesy: theimage.com
Citrine is mostly, and erroneously, called topaz, though both are two
distinct species. Citrine is quartz, and is much lighter than topaz, which
is Hydroxyl Fluorosilicate of Aluminum. Quartz has a Specific Gravity of
2.65 and the Refractive Index of 1.540 to 1.550, whereas topaz has a
Specific Gravity of 3,54 and a higher Refractive Index of 1.620 to 1.630.
True topaz is correctly labeled and some are preceded by two words -
Precious or Imperial. Natural color topaz is known as precious topaz and
imperial topaz, whereas the Imperial Topaz was the topaz with pink tones
which were discovered in the 19th century Russia. Imperial topaz is now
mined at the Imperial Topaz Mines in Minas Gerais, Brazil.
Topaz is an aluminum fluorite silicate - Al2F2SiO4 - and is found in
cavities in granite and rhyolite lava rocks, pegmatites, high temperature
quartz veins, and as worn pebbles in alluvial deposits.
The Origin and Colors of Topaz
The name topaz is thought to come from the Sanskrit word - tapas - which
means fire. In 1 A.D. it was thought that the name was derived from the
Greek word topazos or topazion - meaning to seek - and which was the name of
an island - Topazos Island - in the Red Sea. Today, this island is known as
'Zeberget', or the 'Island of St. John'.
Clear or colorless topaz is quite common and has little value. Blue topaz,
which is very rare in nature, can be made by irradiating clear topaz.
Natural blue topaz is very light in color and irradiation produces blue
topazes of darker hues. Treated blue topaz is available from very light, to
sky-blue, to almost an inky dark blue. These flawless gemstones are
relatively less expensive. The pale or clear topaz that is enhanced to
produce blue topaz is mined in Brazil, Sri Lanka, Nigeria, and China. Blue
topaz is often confused with aquamarine.
The mines in Utah and Mexico produce the reddish-brown topaz. Though not of
high value, they are still more expensive than citrine. Pink topaz is quite
rare and hence is highly valued and occasionally found in jewelry. It is
found in Pakistan and Russia. Pink topaz is also created by irradiating the
common yellow topaz.
Another topaz that is rare is the green topaz, and is highly valued also.
The most prized is the Imperial Topaz, which ranges from red-orange to
pink-orange color. This topaz normally contains many flaws and is very heat
sensitive. Presently, it is mined in small quantities in Brazil.
The other colors of topaz are yellow, brown, orange, beige, and red.
The Deceptive Names of TopazCertain unscrupulous jewelers sell other gemstones, with deceptive names, as
topaz. The names, such as gold topaz, Madeira topaz, Brazilian topaz, Bahia
topaz, citrine topaz, Indian topaz, and smoky topaz are not the names of
topaz. These are just names to deceive you into thinking they are topazes.
Citrine is also sold as topaz under the names - Bohemian topaz, Madeira
topaz, Colorado topaz, Quartz topaz Saxon topaz, Jeweler's topaz, Scotch
topaz, Palmyra topaz, Salamanca topaz, and Occidental topaz. Few more trade
names are Hyacinth topaz, Nevada topaz, and Hawaiian golden yellow topaz.
A variety of quartz are also enhanced and sold as topaz. They go under the
name - Palmeira Topaz, Madeira Topaz, Gold(en) topaz, Rio Topaz, Hinjosa
topaz, Smoky Topaz, Spanish topaz, Scottish topaz, Topaz quartz Orange
topaz, and Topaz saffronite. Poor quality sapphire is also enhanced and sold
as topaz. They go by the names - as Indian topaz, Palmeira topaz, Star
topaz, King topaz, and Topaz cat's eye.
Enhancement of Colorless TopazTopaz is found on most of the continents, with the colorless variety being
the most common. Due to its availability in abundance, it has a very little
value. The colorless topaz is enhanced either by radiation and/or by
heating. The natural blue topaz is of a very pale blue color. Today, a mass
production of a desirable and darker blue color is done through electron
beam enhancement or radiation of colorless topaz. The most common blue
topazes produced by radiation are:
* Sky Blue Topaz - which is a moderately strong light blue topaz resulting
from treating colorless topaz with gamma rays from Cobalt 60 or electrons by
electron accelerators. The treatment is then followed by heat treatment.*
London Blue Topaz - this slightly grayish medium dark to dark blue topaz
results from treating colorless topaz with neutrons produced in nuclear
reactors. This process is also followed by heat treatment.
* Swiss Blue Topaz - is a vivid medium, to medium dark blue topaz produced
by combining neutron treatment with electron treatment, followed by heat
treatment.
After the electron beam treatment, the heat treatment is carried out at
200ºC for many hours. This achieves strong blue colors. After neutron
irradiation, topaz needs a cool off time as it becomes radioactive.
The common yellow topaz, when irradiated converts to pink topaz. Typically,
yellow topaz ranges from wine to straw-colored, and heat-treated yellow
topaz turns reddish-pink. Heating is one of the most common treatments for
topaz. The process can cause the gemstone to change completely, or either
lighten or darken. Normally the heat treatment is irreversible. Heat-treated
topazes are widely available in blues and pinks.
Topaz is not a very expensive gemstone, and with a variety of colors and
sizes available can be an exquisite addition to your wardrobe.
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