Pearl General Category Science

The formation of pearls


Natural pearls: The bead-like particles produced by the endocrine action of the organism in its natural state in the body of mother-of-pearl mollusks are called natural pearls.


Pearls (cultured pearls): In mother-of-pearl mollusks, pearls produced by artificial intervention to promote the endocrine action of the organism are called cultured pearls, or pearls for short.



Famous production areas: Persian Gulf waters west of Iran and east of Saudi Arabia, Sri Lanka, Burma, the Philippines and Australia.

Classification of pearls

Natural pearls and cultured pearls are classified according to the way they are grown.

According to the growing waters, saltwater pearls and freshwater pearls can be classified, so there are saltwater cultured pearls and freshwater cultured pearls, natural saltwater pearls and natural freshwater pearls

According to the presence or absence of nuclei, there are nucleated cultured pearls and non-nucleated cultured pearls

According to the presence or absence of nuclei, they can be classified into free cultured pearls and nucleated cultured pearls



General characteristics of pearls

Chemical composition: CaCO₃ (calcium carbonate) 91.6%, H₂O (water) 4%, organic matter 4%, other 0.4%

Density: 2.61~2.85 g/cm²

Refractive index: 1.490~1.685

Luster: pearl luster

Solubility: blistering with hydrochloric acid

Color: white, pink, light yellow, light green, light blue, brown, lavender, gray and black.

Structural features: pearls can be divided into two main parts: the nucleus and the pearl layer from the inside to the outside.
The innermost layer is the nucleus, and the pearl layer is a crystalline body of keratin and calcium carbonate formed on the surface of the nucleus or foreign body by mother-of-pearl secretions in the process of culturing or growth. Natural pearls and freshwater nucleated cultured pearls generally have a thick layer, while nucleated pearls have a relatively thin layer.


Simple identification of pearls

Smooth and round, with a pearly luster.The pearls are hard and do not break easily.

The pearls are flexible and bounce back to a height of about 37 cm when dropped on a glass plate at a height of 70 cm.

Take 3-5 pearls and put them in a clean glass test tube with an appropriate amount of acetone, hold the test tube and shake it for two minutes, the luster of the pearls will not change.


Care of pearls
In the pearl daily wear storage maintenance methods have the following points of attention.



1.anti-hard object friction, scratching

The surface hardness of pearls is low, so they should not be exposed to coarse structured fabrics and hard objects for a long time.

For example: avoid mixing with other jewelry, do not use toothpaste scrubbing.

2.anti-collision, fall

The pearl layer is a laminar structure, gravity collision, etc., may cause the interlayer structure loose, or even the surface layer off.

3.Corrosion prevention

The composition of the pearl layer is organic calcium carbonate, easy to react with acids and other chemical reactions, so daily wear pearl jewelry should avoid contact with cosmetics, perfume, dye and any other chemicals.

For example, perfume, hairspray, nail polish, vinegar, orange juice, bleach, sulfuric acid and correction fluid, etc. Do not wear pearl jewelry in the shower, doing housework. They should not be placed in cosmetic powder boxes to prevent the pearl surface from being damaged and losing its luster.

During the summer sweating season, after wearing pearls, you should gently wipe the surface of the pearls with a soft wet towel to clean the sweat and keep them after drying in order to maintain the luster of the pearls.

4.Prevent water loss

Pearls should not be exposed to high temperature and sunlight for a long time, which will affect the water of the pearls and reduce the luster.

5.Fixed pearls

Pearl necklace, should pay attention to fixing the pearls, you can tie a knot between each bead, to avoid friction damage between the pearls, while preventing the string line break, to avoid all fall.

6.Wipe with a flannel cloth

When not wearing, do not forget to wipe the surface of the pearls with a flannel cloth to clean the dust, sweat or grease left on the surface of the pearls before putting them in the jewelry box. In case of dirty or dry conditions, wipe the surface with a flannel cloth dipped in a little distilled water (pure water) and keep it after drying.


It is more important to know pearls than to love them.

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