To ensure that the pearls retain their natural lustre, simply wipe them regularly with a cloth soaked in clean, lukewarm water. This will preserve the lustre for centuries.
The most famous pearl "La Peregrina" is over 500 years old. It was worn by queens in England and Spain and by actress Liz Taylor.
The most important basic rule is not to expose pearls to cosmetics, perfume or hairspray. Pearl jewellery should not be worn when bathing or swimming in chlorinated water.
The silk thread used to string the pearl must be checked regularly and renewed every three years.