Pearls are produced by shelled organisms called mollusks that live in aquatic environments. Pearl-producing mollusks include oysters, clams, and mussels, although the production of pearls is rare in the last two.

1. WHAT ARE
PEARLS?

2. Pearls are hard, glistening objects that are produced within the
soft tissue of a living shelled mollusk or another animal, such as
fossil conulariids. They consist of calcium carbonate in minute
crystalline forms, just like the shells of mollusks, which have
deposited in concentric layers. Calcium carbonate is mainly
aragonite or a mixture of aragonite and calcite. The ideal pearl is
perfectly round and smooth, but many other shapes can occur,
and pearls with these other shapes are called baroque pearls,
while those that are perfectly round and smooth are called
regular pearls.

3. The finest quality natural pearls have been highly
valued as gemstones and objects of beauty for many
centuries. This has made the pearl become a metaphor
for something rare, fine, admirable, and valuable.
Pearls come in different colours like white, pink, silver,
cream, brown, green, blue, black, yellow, orange, red,
gold, purple, and iridescent (appear to change colour
gradually as the angle of view or the angle of
illumination changes) - Wikipedia.

4. HOW ARE PEARLS FORMED?
Pearls are formed inside a living creature - an oyster, unlike most
jewelry which are formed from precious metals and jewels that are
found buried in the earth. Pearls are also formed in other mollusks
like clams and mussels, although this is very rare. The formation of
pearls is a biological process; it is the oyster’s way of protecting itself
from foreign substances. The oysters in which these pearls are formed
are found both in freshwater and saltwater environments.

5. The oyster’s shell consists of two parts, called valves.
This makes the oyster a bivalve. An elastic ligament
holds these valves together, and is positioned where
the valves come together. This ligament also keeps the
valves open so that the oyster can eat.
An oyster consists of the following parts: -

6. 1. Mantle
2. Gills
3. Abductor muscle
4. Mouth
5. Stomach
6. Heart
7. Intestines
8. Anus

7. The oyster’s shell is formed by the mantle, using
minerals from the oyster’s food. The material
produced by the mantle is called nacre, and it lines
the inside of the shell. The oyster’s shell grows in size
as the oyster. The nacre is composed of flat layers of
a six-sided crystalline substance called aragonite,
and a very thin layer of the membrane-forming
protein in between the aragonite layers called
conchiolin.

8. When a foreign substance slips into the oyster between the
mantle and the shell, the mantle is irritated. On instinct,
the oyster covers up that irritant in order to protect itself.
The mantle covers the irritating substance with layers of
nacre, the same substance it uses in forming the shell. This
eventually forms a pearl. Pearls are either natural or
cultured. Natural pearls are formed by the oysters on their
own, without any outside interference.

9. Cultured pearls are formed with assistance from
people, often called harvesters. In forming a cultured
pearl a technician with experience collects mantle
tissue from an oyster and inserts a shell bead and a
small piece of mantle tissue into the gonad of a host
oyster. Another method is the insertion of several
pieces of mantle tissue without beads into a host
oyster’s mantle.

10. If a bead is used the mantle tissue grows and
forms a sac around it, and secrets nacre
inward and onto the bead to eventually form
a cultured pearl. If no bead is used, nacre
forms around each of the implanted mantle
tissue pieces. Workers look after the oysters
till the cultured pearls are harvested.
The nacre is formed in layers.

11. TYPES OF PEARLS.
Essentially there are five different types of pearls namely: -
1. Freshwater pearls
2. Akoya pearls
3. Tahitian pearls
4. Golden South Sea Pearls
5. White South Sea Pearls
Now we will take a look at each of these types of pearls.

12. bit.ly/JewelsandPearls