Peridot story, the known facts
by Janna Semenova
August’s Birthstone
Peridot, (pronounced pear-uh-dot) is a French word
derived from the Arabic word "faridat" which means gem. This stone
has been accepted as the birthstone for August and can also be called olivine
or chrysolite. Fine peridot is a rich and beautiful gemstone which is medium
to dark green. Those born in August often suffer from "peridot prejudice"
because they have never seen a fine stone. As early as 1500 BC the Egyptians used
peridot as a gem.
In fact it is now believed that Cleopatra´s emeralds were really fine,
dark green peridots. Peridot was mined in ancient Egypt on an island called
Zeberget. Mining of the stones happened at night because legend said that
peridot could not be easily seen during the day. The island was also
infested with serpents that made peridot mining a very dangerous occupation
until one Pharaoh finally had them all driven into the sea.
The Evening Emerald
The Romans called peridot "Evening Emerald", since its green
colour did not darken at night but was still visible by lamplight. Peridot
later was also often used to decorate medieval churches and probably carried
back to Europe by the Crusaders. Large peridots, more than 200 carats in size,
adorn the shrine of the three magi at the Cologne Cathedral.
Peridot is a very lively stone with many attributes and varieties of colour.
There are more than fifteen shades from olive green, yellow-green,
brownish-green, baby green to a vivid lime green, which is the most valued
colour. The yellowed varieties are often referred to as chrysolite, but are
chemically identical. Peridot is usually lighter in hue than emerald, and
has a more velvety colour rather than a brilliant one.
Throughout history, peridot has been known to have great mystical powers,
which is believed to ward off anxiety, enhance speech articulation, inspire
happiness, strengthen and regenerate the body and mind. It is also supposed
to promote success in relationships and marriage.
The Gem of the Sun
Ancient Egyptians called peridot "The Gem of the Sun" because
it was supposedly too bright to be visible in the sunny Egyptian desert.
Legend also suggests that peridot can glow at night and that was when they
mined for it, so they could easily see it.
There are many legends, which refer to Peridot as having the power to
protect the wearer from evil spirits. And the power was considered even more
intense when the stone was set in gold and had to be pierced, strung on the
hair of a donkey, and worn on the left arm.
According to ancient legends, peridot has the power to protect and purify
and also reduce anger and jealousy. As a medical remedy, it was powdered to
cure asthma. Holding a peridot under the tongue was supposed to lessen the
thirst of a person suffering from fever. The high priest's breastplate,
which is described in the Old Testament Book of Exodus, includes a stone for
each of the twelve tribes of Israel, one being peridot. Peridot is also the
only one gemstone, which has been found in meteorites.
Zebargad, which was known for many years as Saint John´s Island and may have
been mined as early as 1500 BC. The island was discussed in the natural
history of Pliny the Elder (23-79 A.D.) as having been explored in the
fourth century BC. It was called "The Serpent Isle" as it was infested with
many poisonous snakes, which interfered with mining activities. It was said
that one Pharaoh drove the snakes into the sea to get rid off them. However,
the snakes were controlled and mining began in earnest and remained
generally active well into the 20th century.
Recently the stone has become popular possibly because it is now recognised
as the birthstone for August and people who wear the stone will have
success, peace and good luck. It is also the anniversary stone for 14th year
of marriage.
The Mining Sources
The peridot centre is now in Burma, especially around the famous
ruby-producing city of Mogok. However, geologists generally agree that the
best, if not the largest peridot comes from Pakistan. The most abundant
source may be the recently discovered deposits on the San Carlos Apache
reservation in Arizona. Peridot is now mined in many locations including
China, Vietnam, Norway, Brazil, Australia, Hawaii and the Congo.
Native Americans in Arizona on the San Carlos Reservation mine the most
peridot. In 1994, an exciting new deposit of peridot was discovered in
Pakistan that is among the finest ever seen.
The new mine is located 15,000 feet above sea level in the Nanga Parbat
region in the far west of the Himalayan Mountains in the Pakistanian part of
Kashmir. Beautiful large crystals of peridot were found, some that cut
magnificent large gemstones. One stone was more than 300 carats! This new
discovery, combined with fashion´s passion for lime green, has revived
interest in peridot and increased the popularity of this gemstone. Many experts
believe Egypt has the finest crystal specimens, and that Burma has the finest
faceted gemstones.
Properties of Peridot
|
|
| Composition |
Peridot is the gem variety of the olivine group,
which has the following species:
Forsterite – Mg2SiO4 and Fayalite – Fe2SiO4 |
|
|
| Hardness (Mohs) |
6.5 to 7 |
|
|
| Cleavage |
Imperfect to distinct in one direction |
|
|
| Specific Gravity |
3.34 + 0.17, – 0.07 |
|
|
| Refractive Index |
1.654–1.690 (±0.020) |
|
|
| Birefringence |
0.035 to 0.038 |
|
|
| Optic Character |
Biaxial |
|
|
| Crystal System |
Orthorhombic. Perdito usually occurs as rounded pebbles |
|
|
| Colours |
Mainly green, sometimes yellow or brown |
|
|
| Pleochroism |
Weak to moderate |
|
|
| Dispersion |
0.020 |
|
|
| Pleochroism |
Weak to moderate |
|
|
| Handling |
The best way to care for peridot is to clean it
with warm, soapy water. Avoid exposure to heat, acids and rapid
temperature changes. Ultrasonic and steamer are not safe! |
|
|
Buying Peridot
Peridot is probably one of the most popular affordable green stones
on the market today. It is ideochromatic, being colored by the ferrous
iron that is basic to its composition. The ideal color is a rich salad
green, but some peridot is yellowish green, greenish yellow or brown.
The best colors of peridot generally contain about 10–15% of iron and
is priced at USD 30 to USD 175 per carat for sizes under 5 carats.
Peridot is a clean stone, the darker the green the better the stone. Some
peridot can be very light and almost lime green, and thus is not highly regarded.
Peridot is not as light dependent as red and blue gems and it tends to look good
under all lights.
Peridot is occasionally treated with colorless oil, wax, natural and synthetic
unhardened resins into voids to improve appearance. Surface fractures are sometimes
filled with a colorless hardened substance. These treatments should be stable if
done properly.
|
