Pearl is a natural gem and is produced by a mollusc. While the demand of  Pearls in India and elsewhere is increasing, their supplies from nature have reduced due to over exploitation and pollution. India is importing a large amount of cultured pearls   every year from international market to meet the domestic demand. The Central Institute of Freshwater Aquaculture, Bhubaneswar has developed the technology of Freshwater Pearl Culture from common freshwater mussels, which are widely distributed in freshwater habitats throughout the country.

In nature, a Pearl formed when a foreign particle viz., piece of sand, insects, etc. by chance enters into the body of mussel and the mussel can not reject that out and instead makes a shiny coating on the particle layer by layer. This simple phenomenon is being exploited in pearl culture practices.

The Pearl is similar to the inner shining layer of shell called ‘mother of pearl layer’ or nacre, constituted by calcium carbonate, organic matrix and water. The pearls available in the market could be artificial, natural or cultured. Artificial or imitation pearls are not pearls but pearl-like materials that simply contain a rigid, round core or base and an outer pearly coating. In natural pearl the core or nucleus is minute with thick pearl nacre. Generally, a natural pearl is small in size and irregular in shape. A cultured pearl is also a natural pearl, the only difference being the human intervention in surgical implantation of a live mantle graft and nucleus for hastening pearl formation to the desired size, shape, colour and lusture. In India, three species of commonly available freshwater mussels viz., Lamellidens marginalis, L. corrianus and Parreysia corrugata found to produce good quality pearls.

Farming practice of the freshwater pearl culture operation involves six major steps sequentially viz., collection of mussels, pre-operative conditioning, surgery, post-operative care, pond culture and harvesting of pearls, for easier understanding, its has been diagrammatically shown at the end of the page:

Various Factors that decides the Price of Fresh Water Pearl

The grading of fresh water pearls is more variable than that of saltwater pearls. Nevertheless, Freshwater pearls are generally valued according to the

following criteria:

LUSTRE:

The higher and more even the lustre, the greater the value. Low-quality freshwater pearls may seem lustrous to a lay person because often part of their

surface is very shiny. However, if some areas of the pearls look milky, chalky and dull, they are considered to have a low lustre. In high quality fresh

water pearls there is an evenly distributed lustre and a high contrast between the light and dark areas of the pearls.

When judging freshwater pearls for lustre, examine them on a white background and be sure to roll them so you can see their entire surface area. If

possible, compare strands of different qualities. It's important that your eye become sensitive to lustre variations because lustre is one of the most

important determinants of value in pearls of all types.

SMOOTHNESS:

The smoother the pearl, the more valuable it is. Even though bumpy, wrinkled surfaces can lower the value of fresh water pearls the bumps and

wrinkles are not considered flaws.

SIZE/WEIGHT:
Freshwater pearl size is not as important of a price factor as is lustre and surface quality. Freshwater pearl prices are generally quoted by weight or by

the strand. The gram is probably the most common unit of weight used at the retail level, but some dealers quote prices according to carat weight. The

size of round fresh water pearls may be expressed by their diameter, measured in millimetres.


SHAPE:
Usually the more round a pearl is, the greater its value. Good symmetry, too, can make a pearl more valuable. In addition, thin shapes tend to sell for

less than fatter-looking shapes.  Fresh water pearls are baroque shaped. This is the lowest priced shape, all other factors being equal, Large

high-quality, baroque shapes can command high prices and make distinctive jewellery piece. Since 1992, a lot of semi-round (off-round) and oval

freshwater pearls have become available, of late designed pearls are also in demand.

 

SURFACE QUALITY:

Obvious blemishes such as discolorations, pits and cavities can decrease the value of a pearl considerably, especially if the pearl is otherwise of high

quality. Normally, though, flaws in fresh water pearls aren't very noticeable, due to their baroque shapes. Consequently, surface imperfections tend to

have less of an effect on the value of freshwater pearls than on those of saltwater pearls.

COLOR: 

Fresh water pearls come in a wide variety of body colours-white, pink, orange, yellow, lavender, gray Some pearls are even bi-coloured. The body

colour does not affect the price of freshwater pearls as much as it does that of saltwater pearls. The presence of overtone colours such as pink and

silver makes them more valuable. Natural color pearls are more highly valued than those which are dyed and/or irradiated.

NACRE THICKNESS

 Freshwater pearls typically cost less than saltwater pearls. Low prices, though, don't necessarily mean low quality. Therefore don't just judge pearls by

their price tag. Consider their lustre, their colour, their uniqueness. If you do, you'll discover that freshwater pearls offer great variety, beauty and value.

Tests, a Layperson Can Do To Tell The Difference between an Natural and Cultured Pearl

Drill Hole Test:  Look inside the drill hole with a 10-power magnifier. If you can see a dark dividing line separating the nacre from a pearl bead nucleus,

the pearl is cultured. This dark line is conchiolin, the material which binds the nacre to the bead. Natural pearls may show a series of growth lines,

which get more yellow or brown towards the center of the pearl. A black deposit at the center of a white pearl can be a sure sign the pearl is natural.

Also note the size of the drill hole. The drill holes of natural pearls are rarely larger than .04 mm (.016 inch). Those of cultured pearls tend to measure

.06 mm (.024 inch). Natural pearls are partly valued by weight, so the holes are made as small as possible to minimize weight loss.

Shape Test:  Do the pearls look perfectly round? If so, then it's likely they're cultured. Natural pearls tend to have at least slightly irregular shapes,

even though a few are round. This test is only an indication. It is not proof.

Blink Test:  Hold the strand near the front edge of a strong desk lamp. The light should shine through the pearls but not in your eyes. Rotate the

strand. If the pearls blink from light to dark as they are turned, this indicates they are cultured and have a thin coating of nacre (imitation pearls with

mother-of-pearl shell-bead centers may also blink). The dark areas result when there are dense mother-of-pearl layers on the shell bead which block

the light. Cultured pearls with thin nacre may show only one view when rotated. In other words, they don't necessarily blink.

Stripe Test:  As you rotate the pearls with strong light shining through them, look for curved lines and stripes. These are the growth layers of the shell

beads. If they are visible, the nacre is very thin and the pearls are cultured. Not all shell bead nuclei show stripes, though. This can be seen in figure

14.7. Keep in mind that imitation pearls with shell-bead centers can also display this banded effect. Natural pearls, however, will not look striped.

Color Test:  Examine the colour. Cultured pearls often have a faint greenish tint, unlike natural pearls. Some dealers find that the colour of natura

l pearls has a greater potential for brightness than that of cultured pearls. Colour can only suggest a pearl might be cultured. It is not a proof.