Nature
has always provided mankind everything for its survival and sustenance. The
abundance that nature has bestowed upon us can be seen all around. Not only our
basic needs have been taken care of but we have also been gifted with gems and
minerals. These gems and minerals have been unearthed by humans for thousands
of years now for personal adornment and industrial purposes.
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| PEARLS |
This
post of SDI talks about one such gem which has been conferred upon us by nature
– Pearl!
PEARL FORMATION
Pearl
is an organic gem which is found inside a mollusk and is coated with a
substance called nacre which is the secretion of this marine animal. Usually
the mollusks which form pearls have two shells. And natural pearls are formed
without any human assistance.
The process of pearl formation is one of the
most interesting phenomenon that mankind has ever come across. Usually when the
mollusks open their shells to feed and take oxygen an irritant or a foreign
particle enters. This foreign particle enters the reproductive system of the mollusk
and causes irritation. The mollusk
responds by secreting a substance called nacre. Secretion results in creation
of many concentric layers of nacre, which in due course creates a pearl. The
nacre is made up of calcium carbonate and contains a substance which is able to
hold the nacre together – chochiolin. Nacre is what gives a pearl its
characteristic lustre. Nacre is also known as mother-of-pearl which forms the
iridescent lining of the shell.
CULTURED PEARLS
Cultured
pearls can be defined as pearls which have been formed with the help of
human interference in the natural process. Almost all the pearls which are used
for making jewelry today are cultured. Cultured pearls usually are harvested
with the help of a process termed as bead nucleation. Also it requires another mollusk
which is called the ‘sacrificing mollusk’ and it lends its lining tissue to the
other mollusk in which the bead will be planted. Under this process a bead
nuclei which is actually a shell, is surgically implanted in the reproductive
system of a mollusk know as gonad along with the lining tissue. This bead nucleus forms the very core of the
cultured pearls. This surgery is conducted by experts and it takes a time of 2-6
years to harvest the pearls.
There
are two different categories of cultured pearls – saltwater pearls and
freshwater pearls.
SALTWATER PEARLS
Saltwater
pearls are cultured in water bodies with relatively high salt content like
oceans, seas, rivers etc. and take 2-3 years to harvest. There are three types
of saltwater cultured pearls:
Akoya
Pearls: Akoya pearls are considered to be first completely spherical pearls
which appeared in the market in the 1930’s. These pearls have a mirror like lustre
and are cultured with the oyster named pinctada
fucata martensii which are usually found off the seas of Japan and China.
Their size ranges from 2mm – 7mm in diameter. Classic Akoya pearl is white in
colour with a pink overtone. Akoya pearls also come in pink, champagne, silver
and gold tones. The highest quality of Akoya pearls is called hanadama pearls.
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| MIRROR LIKE LUSTRE OF AKOYA PEARLS |
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| PINCTADA FUCATA MARTENSII |
South
Sea Pearls: south sea pearls are majorly cultured in Australia, Indonesia and
the Philippines and in the mollusk called pinctada
maxima. Their size ranges from 8mm – 18mm and they have a soft, satin like lustre.
South sea pearls come in many shades like white, gold, black and black with
different overtones.
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| VARIOUS SHADES OF SOUTH SEA PEARLS |
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| PINCTADA MAXIMA |
Tahitian
Pearls: these pearls are usually grown in black-lipped oysters called pinctada margaritifera. Tahitian pearls
are commonly called black pearls. The body color is usually black with
overtones of pink, green, violet and blue. These pearls are usually harvested
in Cook Islands and French Polynesia and range from 8mm-17mm.
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| TAHITIAN PEARLS |
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| PINCTADA MARGARITIFERA |
FRESHWATER PEARLS
Freshwater
pearls are cultured in freshwater bodies like lakes, ponds and rivers. A
freshwater mollusk can produce up to 50 pearls at a time which greatly helps in
bringing down the cost of pearls. They are relatively cheaper than saltwater
pearls. Also, freshwater pearls do not use a bead nucleus to produce pearls.
Rather they use only a piece of lining tissue from freshwater sacrificing mussels,
so these pearls are made of 100% nacre and due to this reason they are the
closest to natural pearls. The process to harvest these pearls can take as long
as 4-6 years. Freshwater pearls have a rather soft lustre. The highest quality
freshwater pearls are called freshwater orient pearls. The mussel that produces
freshwater pearls is called hyriopsis
cumingi and a few other species like margaritifera
margaritifera. These pearls are majorly cultured in China and on a smaller
scale in US and Japan.
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| FRESHWATER PEARLS |
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| HYRIOPSIS CUMINGI |
Keshi
Pearls: these pearls are accidental by-products of pearl farming and are
supposedly formed both in freshwater and saltwater pearls. These pearls form
under two circumstances. Firstly, when the bead nucleus is rejected by the
mollusk and what remains is the tissue donated by the sacrificing mollusk. As a
result, pearl sac is created. Secondly, the donated tissue gets dislodged
accidentally and again the pearl sac is formed.
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| KESHI PEARLS |
Mabe´
Pearls: mabe´ pearls are commonly referred to as “half pearls” or “blister pearls”.
These are grown in Akoya, South Sea, Tahitian and Freshwater mollusks but the
most famous species in which they are grown are- ptera sterna, ptera penguin and pinctada maxima. These are grown in
a slightly different manner. The bead nucleus is planted between the outer
shell and the inner lining of the shell and hence it grows like a blister. Later,
the blister is cut out, the bead is removed and the hollow area is filled with filler
and covered with a mother-of-pearl backing. These take 2-3 years to culture and
are most suitable for earrings and necklaces.
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| MABE´ PEARLS |
Abalone
Pearls: abalone is a single shelled mollusk and is famous for its unusual
iridescent colour. Most abalone pearls are baroque (irregular shape). It is
difficult to culture abalone pearls because they are haemophiliac. Natural blister
pearls form on the shell. They display a beautiful array of colours like pink,
green and blue.
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| ABALONE PEARL |
One has
to admit that pearls are one of the finest creations of nature. It is a
versatile gem and its soft lustre is timeless. Its subdued glow is like the
light of the moon and represents delicate emotions like love and romance. Pearls
for sure add a magical touch to one’s life.
*The Author is a Colored Stone Graduate from Gemological Institute of America, Mumbai and a Diamond Graduate from Solitaire Diamond Institute, Bangalore. She also holds a Diploma in Jewelry Designing & Manufacturing from Jewelry Product Development Centre, Jaipur. She also blogs at 'The Jewel Affair'
*Picture Courtesy: Google Images
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