Tourmaline is the October birthstone, and those born in
October are indeed very lucky, as they have a beautiful array of colors
representing all the colors of the rainbow and their different shades and
combinations, to choose from. Some of these colors and combinations
are:-red, orange red, reddish orange, orange, yellow, greenish yellow,
yellowish green, green, bluish green, greenish blue, blue, reddish purple,
purplish red, pink, brown, black, and colorless.
The original source of tourmaline was Sri Lanka (Ceylon), a small island
at the southern tip of the Indian Sub-Continent. Almost 90% of the Sri
Lankan soil is gem bearing, and mining had been taking place for thousands
of years. Historical evidence suggests that precious and semi-precious
stones had been exported from Sri Lanka to King Solomon's Kingdom, and
some of
these stones may have adorned the crown of Queen Sheba. Likewise Royal
Families around the world and particularly the British Royal Family had
acquired rare and expensive precious and semi-precious stones from Sri
Lanka since ancient times.
The two main local languages spoken in Sri Lanka are Sinhala and Tamil.
The name Tourmaline is derived from the Sinhala word "Tora malli", meaning
mixed stones or assorted stones of different colors. The term probably was
coined by the early Moor traders, who were the descendants of the
early Arab settlers, who settled in the country between the 5th and 8th
century A.D. and who are considered to be pioneers of the gem trade in Sri
Lanka. Most modern Gemmologists are genuinely puzzled by the abilities
believed to have been possessed by these ancient Moor traders, who were
able to identify accurately both in the rough and cut and polished state,
any one of the variety of gem stones found in Sri Lanka, such as
Sapphires, Rubies, Garnets, Tourmalines, Amethysts, Aquamarine, Moonstone,
Spinel, Topaz etc. These identifications were made without the aid of
instruments that are presently at the disposal of the modern Gemmologists,
for measuring specific gravities, optical properties, hardness etc.
Tourmalines were considered as semi-precious stones since ancient times
and therefore less valuable, but recently it has become a favourite gem
stone in the gem and jewelry trade. This may be because of the wide
variety of colors in which the stone is available, and it's good hardness
of 7.0 to 7.5 on the Mohr's scale. Tourmalines also have healing and other
Metaphysical properties thought to be derived from the electromagnetic
nature of the mineral. This coupled with it's demand as a birthstone for
October, has pushed the prizes of all types of Tourmalines to a level
equal to that of precious stones.
Tourmalines have been used since ancient times by the Aborigines, certain
tribes in Africa, and the native Americans, as a medicinal stone to
relieve asthma, to cure Psychiatric disorders like fears, anxiety,
obsession, and neurosis. The metaphysical properties of tourmaline include
strengthening of body and mind, protection from negative influences,
helping in seeking inspiration, protection against unwanted energies, and
evil forces, protection against dangers and misfortune.
Tourmalines are complex Aluminium Borosilicates with a changing
composition. Many different elements can be accommodated in the crystal
lattice and this accounts for all the different colors in which
tourmalines are found in nature. Some of the elements that can be found in
the Crystal lattice are Lithium (Li), Sodium (Na), Calcium (Ca), Iron
2(Fe++), Iron3 (Fe+++), Magnesium (Mg), Manganese (Mn), Chromium (Cr),
Copper (Cu), Vanadium (V).
Tourmalines are classified according to their colors, but these classes
are sometimes assigned different names.
Red tourmaline - Rubellite
Blue Tourmaline - Indigolite
Green Tourmaline - Verdelite
Green Tourmaline - Chrome Tourmaline (green caused by Chromium)
Yellow Tourmaline - Canary Tourmaline
Brown Tourmaline - Dravites
Black Tourmaline - Schorl
Paraiba tourmaline with an intense blue to bluish green color was first
discovered in 1987,in Paraiba State in Brazil. The blue color is caused by
Copper (Cu), but a certain quantity of Manganese (Mn) may also be present.
If the concentration of Copper is greater than that of Manganese, the blue
turquoise and green color predominates. On the other hand a greater
concentration of Manganese can cause violet, purple, and red hues. However
the violet, purple, or reddish hues can be eliminated by appropriate heat
treatment, leaving only a brilliant bluish or bluish green color. The
color has a unique "fire" and therefore referred to as Neon Or Electric.
The unique properties of Paraiba Tourmalines have made them one of the
most sought after gemstones in the world.
In Brazil the Paraiba is almost exhausted, but new sources of Paraiba have
been discovered in South Western Nigeria. This is not surprising,
because, before continental drift started, the South American Continent
was attached to the African Continent. If on a map of the World, if the
South American Continent is imagined to be shifted eastwards it fits
exactly into the coastline of West Africa. Brazil and Nigeria come closer
together in this imaginary exercise. Thus the Paraiba found in Brazil and
Nigeria probably would have originated at the same time under the same
conditions before the continental drift took place. Therefore the presence
of Paraiba in Brazil and Nigeria provides strong evidence for continental
drift that took place over millions of years.
Sometimes two or more colors can appear together separately in the same
tourmaline. Such stones are referred to as bicolored and multicolored
tourmalines. A special bicolored tourmaline is Water Melon Tourmaline, in
which the outer layer of the crystal is green, and the inside is red, with
black inclusions resembling seeds. Such stones are cut and polished flat
across a crystal face to bring out all the features of the stone.
Tourmalines have two refractive indices-1.616 and 1.652.The difference
0.04 can cause some birefringence leading to doubling of back facets and
inclusions. It has hardness of 7.0 to 7.5 on the Mohr's scale and a
specific gravity of 3.0 to 3.3.
Tourmalines also have industrial applications such as use in high pressure
gauges. The property of tourmaline becoming bipolar when subjected to high
temperature and pressure is made use of in these applications.
Opal
Opal is the alternative October birthstone.
The name Opal may have been derived from the Sanskrit word "Upala", which
means valuable stone. The
Greek word "Opallios", meaning color change, could be another word from
which the term would have
originated.
Since ancient times opals were considered to be healing stones, with the
power to heal depressive
episodes. Opals were also believed to assist the wearers in their quest for
real and true love.
In the past Opals were quite scarce, and the two main sources were Hungary
and Czechoslovakia. But
after the accidental discovery of large deposits of Opal in 1849, in the
deserts of Australia, it
has become a very popular and sought after gemstone. Today Australia is the
world's largest supplier
of fine Opals. Other smaller producers of Opal include the U.S. (Idaho and
Nevada States), Brazil,
and Mexico. Recently Opals have also been discovered in Ethiopia and
Tanzania in East Africa and
Mali in West Africa.
Opals occur in different varieties such as Dark or Black Opal, White or
Light Opal, Milky Opal, Crystal
Opal, Fire Opal etc. The important characteristic of all fine opals is their
unique play of colors,
caused by the dispersion of white light as it passes through the
stone, splitting it into the
different colors of the Spectrum. Opals that do not show the play of colors
are called "Common Opals".
Opal has the same constitution as Quartz, made up of Silicon dioxide
(SiO2),but the silicon dioxide
is always associated with water. Thus Opals are considered to be Silica
Gel, with varying percentage
of water. Therefore Opals should not be exposed to heat for a long
period, as loss of water can cause
fissures in the stone and decrease it's play of color. It is advisable to
wear Opal jewelry frequently
instead of keeping them in storage, for this will help the gemstone receive
water vapour from the
air or the skin of the wearer.
the hardness of Opal is 5.5 to 6.5 on the Mohr"s scale. Thus Opal is a
fairly soft stone, usually cut as cabochons, and prone to wear and tear. Therefore Opal jewelry should be
handled with care, and now they are
sealed with a colorless artificial resin to protect them.
In terms of value Black Opals are the most expensive followed by Crystal
Opal, White Opal, and Milky
Opal.
