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Gemstones
Gemstones are among the most fascinating and exciting of objects.
They have intrigued mankind since before the dawn of recorded
history. Even today nothing creates quite as effective an image of
pure, tangible, concentrated value as a box overflowing with
jewels.
This mystique is unrivaled among the commodities held precious by
mankind. The fact that the mystique exists is seldom questioned,
but its nature is harder to determine. Basically, the entire lore,
history, and value of gems are based on the combination of beauty
and utility they possess. The high value placed on gems since the
earliest time is due to their unique properties. The colors of gem
materials are among the richest and purest in nature.
Gemstones are minerals, the fundamental building blocks of the
earth. A mineral is a naturally occurring inorganic chemical
element or compound, with a definite crystal structure and a
composition that varies within defined limits. Not all minerals
are useful as gems. Since gems must be visually attractive, only
minerals with ornamental qualities are suitable. This criterion
reduces the total available catalogue of about 2,400 mineral
species to approximately 100 that have been cut into gemstones.
Some materials of biological origin are also used as gems. These
include amber, coral, pearl, shells, and jet, a hard variety of
coal.
Gems are evaluated using four basic criteria: beauty, rarity,
durability and desirability. How a gem fares in these four areas
determine its value and overall ranking in the gemstone world. The
basic unit of weighing gemstones is the carat. This is defined as
1/5 of a gram, and is not to be confused with the term ‘karat’
used to describe the fineness of gold. There are 28.3 grams in an
ounce, so a carat is equivalent to about .035 of an ounce.
Gemstones used by Eros:
• Diamond : Diamond is pure carbon, the element that is
also the foundation of life. Diamonds are found in various parts
of the world. In the past centuries fine diamonds came from India.
Diamonds are also found in Africa, Brazil, Venezuela, Guyana,
Borneo, Australia and Russia.
 • Tourmaline : Tourmaline displays the most dazzling and
surpassing variety of colors of all known gemstones. Some crystals
may display two or three color bands along their lengths, or show
complex concentric zoning in cross section. Some of the color
varieties of tourmaline include pink and red (which is also known
as Rubellite), blue, colorless, green, reddish-violet, brown,
yellow, orange, lilac colored, etc. Some tourmalines are also
multi colored or bicolor (Crystals that change color along their
length are called “bicolor” or “multicolored”). Fine tourmaline
comes from Malagasay Republic, South West Africa, Rhodesia,
Mozambique, USA, Maine, California, Brazil and Srilanka.
 • Sapphires : Sapphire comes in a wide variety of color
shades, which includes green, blue, lavender, pink, silver, white
and colorless, etc. All colors of sapphire other than blue are
commonly referred to in the gem world as “fancy sapphire”. Fine
sapphires are mostly found in India, Thailand, Srilanka,
Australia, Myanmar, East Africa, and Cambodia.
• Aquamarine : The color of Aquamarine may vary from pale
blue to rich and deep blue or blue-green. The principal localities
for Aquamarine are Brazil, South-West Africa, India, the Malagasay
Republic, and Russia.
• Garnet : Garnet is a truly ancient gem, known thousands
of years before the birth of Christ. Garnets are not only red;
they may be orange, yellow, brown, pale green, deep green, violet,
purple or even colorless. A good source of Garnet is Arizona,
Colorado, New Mexico in USA, Srilanka, India, Brazil, Alaska and
Africa.
• Smoky Quartz : This stone is believed to have its
color due to the action of radioactivity. Very dark smoky quartz
is known as morion. Fine smoky quartz normally comes from Swiss
Alps, Brazil, Japan, Colorado, Maine, North Carolina and
California.
• Lemon quartz : Lemon quartz derives its color from
irradiation…………
• Citrine: Citrine is yellow quartz, and the color may
grade into smoky brown. The color is due to the presence of Iron.
The primary source of citrine is Brazil.
• Rose Quartz : This occurs in a delicate pink color. The
material is seldom completely transparent, but rather tends to be
somewhat cloudy. The color ranges from nearly white to a deep
rose-pink. The finest rose quartz comes from Brazil, the Malagasay
Republic, Maine and Russia.
• Amethyst : This is the most highly prized quartz variety.
Its color ranges from pale lilac (almost colorless) to a deep rich
royal purple, sometimes showing reddish highlights. The main
source of this stone is Russia.
• Aventurine : Aventurine quartz is found in a wide array
of colors, including green, gold, brown, orange, rust and
blue-green. It is a rock made of interlocked grains of quartz,
containing small crystals of the mineral mica. In some varieties
the mica is a green chrome-rich mineral called fuchsite, which
colors the quartz a rich green. The mica flakes tend to be
oriented in parallel and reflection from the myriad flakes
produces a sparkling sheen. Most of the green aventurine comes
from India.
• Agate : It occurs in a wide assortment of colors, but the
ones most commonly seen are green and blue. Most agates are
banded, though there are exceptions. The finest moss agates come
from India, and from Montana, Oregon, Idaho and Wyoming. Agates
from Arizona, South Dakota, Mexico, and Brazil are known
throughout the world. The variety of patterns and colors is almost
endless.
• Carnelian : This was immensely popular in ancient Egypt.
The color, ranging from light brownish-red to deep clear red, is
due to the presence of iron. Natural carnelian comes from the Ural
Mountains, California, Brazil and Australia.
• Opal : Opal has been called the Queen of Gems. Few
descriptions are adequate to describe the finest opals: a white,
snowy landscape dotted with fireflies of red, gold, blue, purple
and green; a black night streaked in rainbow lightning; the aurora
borealis captured in stone. Opals are found in blue, white and
black color too. By far the finest and most treasured opals come
from Australia.
• Topaz : Topaz is found in a variety of colors. Some of
them are yellow, brown, blue, pink and also colorless. Blue topaz
has become increasing popular these days. Most blue topaz is
fairly pale, but some material can apparently be turned into a
deep color by irradiation with gamma rays. Topaz occurs in many
localities through out the world. Brazil is the chief supplier of
colorless, pale-sherry and blue varieties. Ouro Preto, Brazil is
the world’s chief source of fine gold and yellow topaz.
• Chalcedony : This is one of the most commonly found
quartz and occurs throughout the world. Chalcedony is hard, tough,
and durable. Its fine grain allows for intricate and detailed
carving and design. It was supposed to cure insomnia, breed
prudence and caution. It is found in Brazil, Uruguay, India,
California, Australia, Mexico and Germany.
• Moonstone : Moonstone has a blue or white sheen, which is
called adularescence. Moonstone may be completely transparent, and
the sheen may be either silvery white or a soft, but distinct
blue. Some moonstones are nearly opaque and may have a strong body
color, which may be beige, pink green, white, yellow, gray or
brown. Moonstones with a strong body color are primarily found in
India. The most important historical sources of this stone are
Srilanka and upper Burma. Other sources include Canada,
Switzerland, Brazil, Australia, California, Virginia and Colorado.
• Peridot : Peridot is a warm, soft olive or
yellowish-green gem. Peridot tends to have a soft velvety
appearance that helps distinguish it from similar – appearing
materials such as tourmaline and glass. Fine Peridot of a pleasing
color comes from Arizona. Small amounts of peridot have also been
found in Brazil, Australia, Czechoslovakia, Hawaii, Norway, Zaire
and Mexico.
• Turquoise : This has been a prized stone since remotest
antiquity for its superb blue color. Some of the world’s finest
turquoise comes form northeastern Iraq (Persia). USA is a major
world source for turquoise. Minor amounts are also found in
Australia, China, Tibet, Peru, Mexico and Chile.
• Rhodolite : Rhodolite is a variety of red garnet. Its
color is violet-red or purple, the hue sometimes resembling that
of amethyst. Localities include Thailand, Brazil, Ceylon and
Africa.
• Iolite : Iolite is considered a gem with very strong
pleochroic properties, meaning it may show many colors from
different angles. The predominant color is blue, which flashes of
violet, gray, or yellow, or all of these. Localities include
Brazil, India, Burma, Norway, Finland, and the Malagasay Republic.
• Lapis Lazuli : Lapis was one of the most precious
commodities of the ancient world, and was even valued on an equal
level with gold. The brassy-gold spots of flecks of pyrite in
genuine lapis are very distinctive. The finest lapis is a dark
blue color with a violet cast, uniformly colored and displaying no
white spots. Lapis is mostly found in Afghanistan, southern
California, Pakistan, Burma, Angola and the Andes mountains of
Chile.
• Onyx : the rich black gem that the whole jewellery world
knows as onyx usually isn’t onyx at all, but rather a form of
agate that gets its uniformity of color through a relatively
simple method of treatment. Brightly colored onyx in shades of
blue, red, green, and yellow is dyed. South America is generally
considered the world leader in onyx production.
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