About Freshwater Cultured Pearls
Wild, or natural, pearls are formed when irritant, like a piece of shell, bone, coral or parasite, is taken in by an oyster, or mollusc, and lodges inside its shell. The oyster responds by coating the irritant with a layer of nacre, or mother of pearl. Over time, more and more layers of nacre are laid down over the irritant until it becomes a pearl.
Cultured pearls are made in exactly the same way as natural pearls. The only difference is that in cultured pearls the irritant is artificially inserted into the mollusc to start off the process.
To make a cultured pearl freshwater molluscs are implanted with a small piece of nacre producing tissue from another mollusc. The pearl can take up to six years to grow and by the time it is harvested the implanted tissue has disappeared leaving behind a solid pearl. This means that the surface of this type of pearl will not reveal the inner irritant if it wears away.
Cultured pearls are grown in inland lakes and rivers hence the name freshwater pearl.
Only about 5% of seeded molluscs actually produce a good quality pearl. This makes them expensive to buy. However, they are much more affordable than wild pearls.
The colour of a pearl depends on the breed of the mollusc, the diet, water temperature and pollutants in the water. Most beads are muted or pastel colours. The bright colours are created by dying the pearls after harvesting.
Looking after pearls
Pearls needed to be treated with care as their surface lustre can easily become chipped or scratched. They should be stored away from other jewellery and wrapped in a soft cloth, to protect them from damage. They should also be cleaned every now and then using a mild detergent and a soft cloth.
It is advisable not to wear pearls with perfume or body oil as this can affect their surface lustre.
Pearls are often strung with knots between them; this stops them from rubbing together and wearing against each other. It also means that if the string breaks the whole length of pearls are not lost.
Types of pearls
There are several different types of pearls: