Agate Facts and Buying GuideBy:Sheweta Dhanuka
Summary: The variety of colours found is immense yet some common colours are green, yellow, purple, black, orange, brown, red, reddish-brown, white and bluish-white etc. Colour change takes place due to change in the impurities and its content in the chemical composition such as red occurs due to presence of either one of the mineral viz. iron, chromium, cobalt or cooper.
Agate is an innovatively created gemstone by the nature. It belongs to
the chalcedony quartz family. It was found thousands of years ago in Achates
River in southwestern Sicily that is now know as Dirillo River. The name
Agate is derived from the initial name of the river-achates. It is the
birthstone for the month of May and anniversary stone for 12th year of
marriage.
This is an attractive semi precious gemstone with huge diversity in it.
Easy availability, moderate price, good looks etc are few features that make
it well liked in the circle of gemstone lovers. It is a simple stone without
much specification hitherto general awareness about it is essential while
making the purchase. This article provides the all-purpose information that
could also be used as buying guide. Agate occurs in many different forms but
here only few imperative varieties are mentioned. The characteristics
discussed are about Agate as a whole not specific to any one single variety.
Varieties - It is procured in varied forms. To know this gemstone
well, one has to be aware of its varieties too. All forms are used as
gemstone and ornamental stone. These differ from one another due to the
change in impurities in the composition. The varieties are differentiated on
the basis of colour of the bands.
Moss Agate: It is a clear stone, green in colour and contains
visible impurities. It is also known as Mocha stone. This is the
most-sought-after variety. It is considered close to nature and said best
suited for those related with agriculture industry. Helps in creating the
balance within the sides of brain.
Dendritic Agate: It is black or white in colour. The structure of
this form of Agate is that of tree with trunk having big and small branches.
It contains manganese oxide impurities that form the fabrications and so on.
Riband Agate : In this gemstone, the bands are broad and appear as
straight lines across the gemstone. It is also known as ribbon agate.
Ring Agate : As the name suggests, it comprises of bands in form
of concentric circles in varied colours. It is also called as eye agate.
Plume Agate: It is named after its plume like shape. Colour varies
from shades of blue, white, yellow and red. United States of America is the
primary source for this variety.
Fire Agate: The formation process of this variety is quite
distinctive. Like all it is also produced during the volcanic eruption or in
basalt. It is layered in one micro-thin layer in vugs from hydrothermal
solution at a time. Similarly few more layers are formed then among these
layers some reflect light back in the pattern of rainbow giving rise to
bubbles and sheets of different colours viz. brilliant blue, red, yellow and
green.
Colour - This fascinating gem is available in varied colours. The
variety of colours found is immense yet some common colours are green,
yellow, purple, black, orange, brown, red, reddish-brown, white and
bluish-white etc. Colour change takes place due to change in the impurities
and its content in the chemical composition such as red occurs due to
presence of either one of the mineral viz. iron, chromium, cobalt or cooper.
Black owes its colour to iron and manganese. Green is due to iron, chromium,
nickel and copper while blue is because of iron, titanium and cooper. Iron
oxide leads to brown, chromium to yellow and manganese to pink and violet as
well. Apart from the impurities, colour is also affected by change in
temperature, radiation, pressure and weather.
Bands are the distinctive feature of this colourful gemstone. Each and
every stone possess concentric bands in different colours and textures.
These bands are formed when impurities reacts with the solidifying gel in
the volcanic lava at the time of crystallization. Difference in bands occurs
because of the variations in the impurities and its content in the
composition of the stone. This process is entirely natural therefore no two
stones would have similar bands. Furthermore the pattern of bands is
irregular. It could be circular, patches or haphazard lines etc.
Clarity - It is vitreous to glassy in luster. Being, translucent
or opaque in nature the presence of flaws or inclusions is not of much
significance. Moreover, while processing the rough into a gemstone, through
cutting and polishing the presence of flaws further becomes unnoticed. In
this stone clarity is not much helpful while making the purchase of a
genuine stone.
Cut - This trait is very crucial. The end look of the stone is
reliant on the cut it is given. The natural bands of stone are enhanced if
given the appropriate cut therefore; cutters have to concentrate on the
bands while cutting. It is a hard stone thus, it can be given any shape like
round, pear, square, emerald and so on.
Carat Weight - In natural state this marvelous gem is found in
large and massive form. At the time of preliminary gemstone processing, the
rough is cut and polished to create medium and smaller stones of different
carat weight. As per one's pocket one can select the suitable stone of any
carat. Gems between 2-4 ctw are apposite for the jewelry items and gives
splendid look as well. This weight is neither less nor more and is
affordable too. The stones used for creating the ornamental pieces has to be
between 4-9 carat or even more.
Price - This awesome gemstone could be acquired easily as it is
available at reasonable price. Only few stones with extraordinary bands or
scenes are priced more yet affordable. The price is ascertained on the basis
of carat weight, cut and bands structure. Price increases with the increase
in carat weight. A good cut that highlights the bands enhance the beauty of
the gem hence is worth more. Bright stones consisting of unusual and
exclusive bands are valued more in terms of money. The sculptures and carved
pieces made of one single solid piece are priced higher than those items
where more than one stone is used.
Occurrence - It generally occurs as rounded nodules or veins. It
comes into existence during the volcanic eruption in the cavities of
eruptive rocks or the volcanic lava. After the volcanic eruption, flowing
lava starts solidifying then few gas bubbles are trapped in it. These
bubbles later are filled with alkali and silica-bearing waters, which set as
gel. Then alkali and iron present in the surrounding lava reacts resulting
iron hydroxide forming the bands within the gel. Finally, gel looses water
and crystallization occurs leaving the bands in one piece. It forms in
shallow depth and low temperature.
Source - This colourful gemstone was first mined at Nahe River
valley in Germany. Nahe deposits are now said to be exhausted. Today, it is
found across the globe. The next larger producers are Brazil and Uruguay.
Some other countries proffering agate are Mexico, Egypt, Congo, Italy, India
and Nepal. It is generated in immensity at Oregon, Washington, Idaho and
Montana states of USA.
Enhancements - It is porous in nature thus, often artificially
stained or dyed to enhance the appearance. Enhancement helps in increasing
the net value of the gemstone. The skilled people perform all the treatments
and the retention of the changed appearance of the stone lasts for many
years.
Imitations - This gemstone comes in many different colours. It is
procured quite easily. It is priced moderately still many jewelers sell poor
quality stone as agate. Glass agate and Iceland agate are basically poor
quality of obsidian that are treated and later sold as agate. Similarly,
glass opal stimulant is named as Lake Superior fire agate or Mexican agate
and sold at the price of pure agate.
Use - It has jewelry, ornamental and industrial use. Treasured a
lot by the lapidaries. Carvings, cameos, intaglios and beads made up of this
gemstone cherished by many people. As ornamental use, splendid figures and
sculptors are created from large stones. Agate bowls, letter openers,
crockery handles, paperweights, bookends and guitar picks are also fairly
popular. These are ideal for decorating the house, office and guesthouse
etc. Beads are created in striking cabochon shape are used for making
exquisite flat or rounded ornaments. Apart from cabochon, other possible
shapes are oval, round, baroque and square. The size varies between 1mm to
9mm. Bracelets and necklaces of beads are pretty in demand among the females
in almost every corner of the world for casual and professional attire.
Handcrafted jewelry items are made from the well-created stones of
different carat weight. Earrings, pendants, broaches and rings made from
this gemstone are likes by females in every corner of the globe. It is
idyllic for jewelry worn for daily basis. Sterling silver, 18K yellow gold,
18K white gold and platinum are used for making these ornaments. However,
silver is used maximum amongst all the accessible metals. The reason being,
silver enhances the beauty of the gem more than yellow gold. White gold and
platinum are used less because two of these metals are not suitable in the
economic terms. For industrial purpose, it is used in the manufacture of
grinding equipment.
Precautions - It is rated between 6.5-7 Mohs on the hardness
scale. Its hardness rate specifies it as sturdy and long-lasting stone.
Therefore, any specific care is not required yet general gemstone
precautions are essential for the lifetime retention of the stone. Although
the gem is hard and do not requires much care but by taking the precautions
the gem and its jewelry would always look as up-to-the-minute.
Beliefs - In ancient times it was used as powerful amulet or
talisman to protect the wearer from all dangers and provide necessary
strength. European royal families had passion for collecting bowl made up of
Agate that can be seen even today in European museums. In past people used
to wear it in order to attain the power to overcome the enemies and acquire
wealth. Greeks used it for protecting themselves from hazards of sea.
Today astrologers suggest this stone for curing all sleep allied problems
like nightmares, bad dreams etc. It is also helps in remedy of insomnia and
pancreas turmoil. Blood circulation smoothens by wearing this colour
versatile gemstone. Apart from the medical treatments, it creates the
balance between the physical, emotional and spiritual state of the wearer.
Enhances the analytical ability and improves perceptiveness. It eliminates
and cleanses the negative energies from the body.
This multi-faceted gemstone is plain and elegant. It can be worn on
different occasions. Try wearing this marvelous gemstone and experience the
feeling of eternal joy and happiness. Worth trying !!
Agate Facts
|
Chemical Composition |
It is silicon dioxide and
the chemical formula is SiO2. |
|
Colours |
Green, yellow, purple,
black, orange, brown, red, reddish-brown, white and bluish-white. |
|
Streak |
White. |
|
Refractive Index |
1.545 - 1.554 |
|
Specific Gravity
|
2.57-2.64 |
|
Luster |
Vitreous to greasy.
|
|
Solid State |
Translucent. |
|
Crystal System
|
Trigonal. |
|
Hardness |
6.5-7 Mohs |
|
Cleavage |
None. |
|
Fractures |
Conchoidal. |
|
Luminescence |
None |
|
Birefringence |
Weak, between 0.005-0.009 |
|
Enhancement |
Regularly dyed or stained
to improve the colour. |
|
Source |
Germany, USA, Brazil,
Uruguay, Mexico, Egypt, Congo, Italy, India and Nepal |
|
Precautions |
General gemstone
precautions to be taken. |
Related Links :
|
 |
Belly Button Piercing The Egyptians, the Indians and many other cultures pierced this humble button to show the significance of the person sporting a pierced navel - Royalty, Warriors, exceptional Beauty. |
|
|
|
|
|