Never use an ultrasonic cleaner on your pearls. It can damage their nacre. Occasionally wipe your pearls gently with a cloth dipped in mild, soapy water. Then rinse the cloth in fresh water and wipe the pearls clean. Dry them with a soft cloth.
If pearls come into contact with an acid substance such as fruit juice, vinegar, or other chemicals, immediately wipe clean with a soft cloth. Be careful not to submerge your pearls in water as this will weaken the silk thread.